Category Archives: Game Design

A Human-Level Intelligence at Gettysburg, Day 3

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Screenshot of MATE analysis of Gettysburg, Day 3 from the Red (Confederate) position. Click to enlarge.,

General Lee, at Gettysburg, said: “the enemy have the advantage of us in a shorter and inside line and we are too much extended.” – quoted by Major General Isaac Trimble.1)Isaac Trimble, Southern Historical Society Papers, Vol. 26, Richmond, Virginia: Reverend J. William Jones, D.D., MATE, the AI behind General Staff, came to the exact same conclusion:

A portion of MATE’s analysis of Red’s position at Gettysburg, Day 3. Here MATE recognizes that Red has exterior lines and the enemy has a decided advantage.

I have been porting TIGER 2)Tactical Inference GenERator, the AI behind my doctoral thesis and my DARPA sponsored research from C++ to C# and integrating it into the General Staff: Black Powder wargaming system. I have been doing this via the method of first creating a scenario typifying a specific attribute (exterior lines, exposed flanks, choke points, etc.) and then porting the actual code over and feeding it the scenario for analysis. Gettysburg, Day 3, is the canonical example of exterior and interior lines.

92.9% of Subject Matter Experts agree! The Union (Blue) lines at Gettysburg, Day 3, exhibit the attribute of being Interior Lines. Interior lines are good. Exterior lines are bad. From author’s doctoral thesis.

So, first a significant number of Subject Matter Experts (combat commanders, tactics instructors at military academies, etc.,) agree that there is an attribute called ‘Interior Lines’ and that it is exhibited by the Union (Blue) forces at Gettysburg, Day 3. We then create an algorithm that can detect such an attribute and convert it from C++ code to C# code (and substantially rewrite and improve said algorithm in the process) . We then create a Gettysburg, Day 3 scenario using the General Staff Army Editor, the General Staff Map Editor and the General Staff Scenario Editor and feed the scenario3)In Computer Science lingo programs are machines that consume data / tokens to MATE, the General Staff: Black Powder AI. These are the results:

MATE analysis text output (with author’s commentary) of Gettysburg, Day 3, from the Red (Confederate) position. Click to enlarge.

The first time that I presented the Gettysburg, Day 3 scenario as Red to MATE it refused to attack. The enemy has interior lines (1.4, or 40% greater is pretty significant value), you’re attacking uphill (slope > 7%), your attacking units are under enemy ROI (mostly batteries of 12 lb. Napoleon canon shooting explosive shot and then canister and then double-shotted canister) for over a kilometer. Attacking is not a good idea. To get MATE to attack I had to go back to the Map Editor and create a number of new Victory Points; specifically the places where significant roads (Emmitsburg Road, Cashtown Road, Baltimore Pike, etc.) enter the map. Then I went in to the Scenario Editor and assigned appropriate values and current ‘ownership’. Saved it all and fed it back to MATE and the, above, is what I got.

The only way for MATE to win (as Red) is to attack large Victory Point areas (Cemetery Hill and Cemetery Ridge) and hope to destroy significant numbers of Blue (Union) forces along the way to meet the victory conditions set in the Scenario Editor:

Gettysburg, Day 3 Victory Conditions. Screenshot General Staff Scenario Editor.

Anybody who has built a wargame scenario (and I suspect there are more than a few among the readers of this blog) know the drill of going back to edit the OOBs, starting positions, victory conditions, etc. I would just like to say it’s pretty painless using the General Staff Wargaming System. The various editors all integrate seamlessly like Microsoft Office products (they were written in Microsoft WPF by Andy O’Neill who is a Microsoft Gold Developer).

But, the real question that this raises is: why did Lee attack on Gettysburg, Day 3? Blue (the Union) not only had interior lines, an elevated position, but they also had anchored flanks (see #22 above). MATE is running out of options at this point. If you look at the top screenshot you will see yellow numbers in yellow circles. These represent MATE’s three ‘weakest points’ in Blue’s line and it’s not much.

So why did Lee attack?

James Longstreet’s From Manassas to Appomattox states absolutely that

All that I could ask was that the policy of the campaign [Lee’s invasion of the north] should be one of defensive tactics, that we should work so as to force the enemy to attack us, in such good position as we might find in his own country, so well adapted to that purpose, – which might assure us of a grand triumph. To this he readily assented as an important and material adjunct to his general plan. [p. 331]

So, Longstreet, in his autobiography, is saying that Lee agreed that at some point in Pennsylvania, the Army of Northern Virginia would find a good solid defensive position and let Hooker (they didn’t yet know that Meade was the new commander of the Army of the Potomac) smash his army to pieces upon it. James McPherson in,  To Conquer a Peace: Lee’s Goals in the Gettysburg Campaign writes:

“In a conversation with General Isaac Trimble on June 27, when most of the Army of Northern Virginia was at Chambersburg, Pa., and when Lee believed the enemy was still south of the Potomac, he told Trimble: “When they hear where we are, they will make forced marches…probably through Frederick, broken down with hunger and hard marching, strung out on a long line and much demoralized, when they come into Pennsylvania. I shall throw an overwhelming force on their advance, crush it, follow up the success, drive one corps back on another, and by successive repulses and surprises, before they can concentrate, create a panic and virtually destroy the army.” Then “the war will be over and we shall achieve the recognition of our independence.”

The argument is that Lee, on the morning of July 3, 1863, found himself in a terrible strategic situation with very few options. It was imperative that Lee must, “destroy the [enemy] army;” nothing less than a great triumph in enemy territory would do. In Lee’s only official report of the battle of Gettysburg, written on July 31, 1863 he states:

The enemy was driven through Gettysburg with heavy loss, including about 5,000 prisoners and several pieces of artillery. He retired to a high range of hills south and east of the town. The attack was not pressed that afternoon, the enemy’s force being unknown, and it being considered advisable to await the arrival of the rest of our troops. Orders were sent back to hasten their march, and, in the meantime, every effort was made to ascertain the numbers and position of the enemy, and find the most favorable point of attack. It had not been intended to fight a general battle at such a distance from our base, unless attacked by the enemy, but, finding ourselves unexpectedly confronted by the Federal Army, it became a matter of difficulty to withdraw through the mountains with our large trains. At the same time, the country was unfavorable for collecting supplies while in the presence of the enemy’s main body, as he was enabled to restrain our foraging parties by occupying the passes of the mountains with regular and local troops. A battle thus became in a measure, unavoidable. Encouraged by the successful issue of the engagement of the first day, and in view of the valuable results that would ensue from the defeat of the army of General Meade, it was thought advisable to renew the attack. . . .

Lee was in for a penny and in for a pound. This was not the defensive battle of Longstreet’s choosing. This was now Lee desperately trying to, “throw an overwhelming force on their advance, crush it, follow up the success, drive one corps back on another, and by successive repulses and surprises, before they can concentrate, create a panic and virtually destroy the army,” but now the enemy had, “retired to a high range of hills south and east of the town.” The Union had flipped Longstreet’s strategy 180 degrees and it was they who had, “force[d] the enemy to attack [them], in such good position as [they] might find.”

I will create some other Gettysburg scenarios including ones with the Union and Confederate cavalry available. While not historical, it might make for some interesting gameplay and Human-Level AI decisions.

As always, please feel free to contact me directly with comments.

References

References
↑1 Isaac Trimble, Southern Historical Society Papers, Vol. 26, Richmond, Virginia: Reverend J. William Jones, D.D.,
↑2 Tactical Inference GenERator
↑3 In Computer Science lingo programs are machines that consume data / tokens

General Staff will Ship in 2022

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A few of Grant’s unsuccessful attempts to take Vicksburg. Map from West Point Atlas of American Wars. Library of Congress. Click to enlarge.

Grant took Vicksburg on his sixth attempt. He first tried a direct movement, east of the Mississippi, against the city but was forced to turn back after Confederate General Van Dorn’s raid destroyed his supply base. Sherman next attempted a direct assault and failed at Champion’s Bluff. Grant then tried to cut Vicksburg off from the Mississippi by digging a great canal across the neck of a giant oxbow. Unusually low water levels in the river that year caused another failure. Grant also tried more canal digging and river clearing at Lake Providence and the Yazoo Pass without luck.

Col. Theodore Lyman, a staff officer of the Army of the Potomac, wrote of Grant, “He habitually wears an expression as if he had determined to drive his head through a brick wall, and was about to do it. I have much confidence in him.”

Grant finally succeeded with his brilliant amphibious landing south of Vicksburg followed by a series of ‘must win’ battles that concluded with besieging the city on May 22, 1863. Confederate General Pemberton surrendered Vicksburg on July 4, 1863.

The General Staff: Black Powder Wargaming System is comprised of four separate programs: the Army Editor, Map Editor, Scenario Editor and the actual Game Engine, itself. The first three have been done for some time (it’s what I use to produce scenarios for testing the AI). They were written in C# using Microsoft’s Windows Presentation Foundation (WPF) which is often used for creating desktop business applications. This decision made sense because the Army, Map and Scenario Editors function not unlike a suite of business applications that create and share data with a common look and feel. However, while WPF was a good development decision for the Editor programs it turned out not to be a great tool for creating the Game Engine.

A flow chart of the General Staff: Black Powder Wargaming System. Files created in the Army Editor and the Map Editor are combined in the Scenario Editor to create a scenario or simulation. Click to enlarge.

What the Game Engine does is it takes data created in the three Editor programs, displays them in a visually exciting way, enables the user to make input (orders), and simulates those orders (as well as the AI’s orders) and the resulting combat to the highest degree of accuracy possible. That sounds like a lot, but it really isn’t. And the heavy lifting that the Game Engine is being asked to do is all visual: making everything look good on the screen.

Recently, I’ve been looking at Grand Tactician: Civil War which is an immersive voyage into 19th century American typography, cartography, tactics and grand strategy. I eagerly look forward to having the time to do more than gaze upon it in amazement 1)Full disclosure, the developers were kind enough to give me a review copy of Grand Tactician and, damn, it looks fantastic.. I reached out to Ilja on their development team and he convinced me that we should complete the General Staff Game Engine in Unity (which is what they used for Grand Tactician). What they accomplished visually with Grand Tactician was precisely the look and feel that I wanted for General Staff 2)I’m talking about the typography and the UI, not thousands of tiny 3D soldiers on the battlefield; which look really great, but, General Staff is not that kind of a wargame..

Consequently, we are officially announcing that we are abandoning writing the General Staff: Black Powder Game Engine in WPF and, instead, will be creating it using the Unity engine. We believe that this will produce a far superior visual experience 3)Please note: we will not being using Unity to create a 3D simulation with tiny soldiers. I like playing those kind of games, but that’s not what General Staff is..

Because Unity is designed to facilitate the creation of computer games, this move will greatly accelerate the completion of the General Staff Game Engine and will allow us to ship General Staff: Black Powder this year.

I am certainly not U. S. Grant, though I like to think I have some of that bulldog determination. Like Grant before Vicksburg, I’ve had to acknowledge that our first attempt will not succeed and we’re moving on to another plan. I am sorry for the delay in the release of General Staff and am confident that, with Unity, we will soon be reporting some good news.

I am also very excited to announce that my good friend, Damien, will be joining the team to specifically work in Unity completing the General Staff Game Engine. Damien lives in Ireland and has been a devout wargamer since playing Arnhem on the ZX Spectrum. When not enjoying a Guinness or a Jamesons, he’ll be playing tabletop or computer games, whether that means pushing cardboard counters across hex boards, drawing LOS between badly painted miniatures on the tabletop, or day-long sessions in front of a computer – where he particularly enjoys playing against a challenging, non-cheating AI. Damien is a 28 year veteran of the IT industry, having worked on everything from telecoms, healthcare and financial systems, across Mainframes, Linux, Unix and Windows, and co-inventor of two messaging system patents. He has a particular passion for language processing and domain specific languages, originating from his interest in the elegance of recursive descent compiler construction.

References

References
↑1 Full disclosure, the developers were kind enough to give me a review copy of Grand Tactician and, damn, it looks fantastic.
↑2 I’m talking about the typography and the UI, not thousands of tiny 3D soldiers on the battlefield; which look really great, but, General Staff is not that kind of a wargame.
↑3 Please note: we will not being using Unity to create a 3D simulation with tiny soldiers. I like playing those kind of games, but that’s not what General Staff is.

I Was Wrong About George Washington

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Washington Crossing the Delaware by Emmanuel Luetze. 1851. The Metropolitan Museum of Art. Click to enlarge.

I must confess that I was never much a fan of George Washington’s generalship. Having not studied American Revolution military history I thought that from 1776-1781 the British chased Washington and his sad excuse for an army up and down the eastern seaboard of what was to become the United States until the French Comte de Grasse defeated the British naval forces at the Battle of the Chesapeake and the Comte de Rochambeau at the head of a French army surrounded, besieged and eventually captured, Cornwallis at Yorktown.

To make matters worse, years ago I stumbled upon George Washington’s Expense Account which is, frankly, brutal. Washington turned down the magnanimous salary of $500 a month for being Commander in Chief of the Continental Army famously saying,

“As to pay, Sir, I beg leave to Assure the Congress that as no pecuniary consideration could have temped me to have accepted this Arduous employment (at the expense of my domesttic [sic] ease and happiness) I do not wish to make any Proffit [sic] from it. I will keep an exact Account of my expences. Those I doubt not they will discharge, and that is all I desire.” 1)George Washington’s Expense Account, Washington, George & Kitman, Marvin, page 15

If Washington had accepted the salary he would have been paid $48,000 for five years’ service. Instead, his ‘expences’ came to $449,261.51! This book – and it contains a photocopy of every page of Washington’s Expense Account in fine copperplate handwriting along with a humorous explanation of the expense – is damning. Washington’s very first entry for June, 1775 was for $6,214 (over an entire year’s salary at $500 per month) for “…the purchase of five Horses… to equip me for my journey to the Army at Cambridge – & for the Service I was Then going upon  – having sent my Chariot and Horses back to Virginia.” There are also numerous expenses for cases of the finest wines and plenty of food while at Valley Forge. Not surprisingly, when Washington offered Congress the same terms when he was elected president (no salary just expenses) Congress insisted that he take $25,000 a year; no expenses paid.

Like most Americans, what little knowledge I had of the battle of Trenton can be summed up in Luetze’s famous painting, above: Washington, posed heroically, crossed the Delaware River on Christmas Eve and surprised a garrison of drunken Hessian mercenaries at Trenton capturing them all without a shot. In reality, not much of that is true. Yes, Washington did attack Trenton but it was on the morning of December 26, 1776, and the Hessians weren’t drunk; they fought bravely and their commander, Col. Johann Gottlieb Rall, died leading them.

Then I discovered (from reading David Hackett Fischer’s Pulitzer Prize-winning Washington’s Crossing) that the amazing part of the story wasn’t the battle of Trenton (which really was an extraordinary tale of a small, poorly-equipped, non-professional army making an audacious amphibious crossing of an ice-choked river) but the campaign that followed the victory from December 30, 1776 to January 3, 1777.

The strategic situation in the Princeton / Trenton area, December 29, 1776. Screen shot from the General Staff Scenario Editor. Click to enlarge.

Washington’s forces had made it safely back across the Delaware River after the Trenton raid but he now faced a difficult decision: terms of enlistment were running out for many units in his army and he feared taking the field again in bitter cold with a diminished force. As always, Washington held a council of war. As the senior commanders of the army advised caution a courier arrived informing them that Brigadier General John Cadwalader with his Pennsylvania militia had already crossed the Delaware and was at Crosswicks itching for a fight with the British (this is the blue force at the bottom of the map, above). After more discussion, one group stated, “tho’ they would not have advised the Movement, yet it being done it ought to be supported.”2)Washington’s Crossing, David Hackett Fischer page 266. Eventually, with Washington’s urging, the council voted to support Cadwalader, recross the Delaware and, again, defeat the British in the field.

This was a bold strategy; a defeat of the Continental Army with its back to a river would probably spell the end of the revolution. Washington’s plan was to assemble his forces east of Trenton, in a strong defensive position on ‘good ground’ behind the Assunpink Creek and lure Cornwallis, who was commanding the British and Hessian forces, to attack. This Cornwallis did and was soundly defeated. Washington now moved decisively, sending his forces to capture Prince Town (Princeton) to the north. At the crucial moment in this battle Washington rallied the routed Pennsylvania forces saying, ” ‘Parade with us, my brave fellows! There is but a handful of the enemy, and we will have them directly.’ Washington [then] led his men straight into the center of the battle, within thirty paces of the British line. He was mounted on a white horse, an easy mark for any British soldier.”3)Ibid. page 334

Frankly, I cannot comprehend such bravery. The attack, of course, was a success and the Americans captured Princeton and, perhaps more importantly, demonstrated that their volunteer army would fight, could fight and could win. Washington showed superb strategic and tactical vision throughout these ten crucial days4)See https://tencrucialdays.org/wp-content/uploads/2019/09/eb14b5212fb62dfea8d100f3efd1950f.pdf  for a wonderful series of maps that cover this campaign as well as extraordinary personal courage.

I was wrong about George. Washington.

References

References
↑1 George Washington’s Expense Account, Washington, George & Kitman, Marvin, page 15
↑2 Washington’s Crossing, David Hackett Fischer page 266
↑3 Ibid. page 334
↑4 See https://tencrucialdays.org/wp-content/uploads/2019/09/eb14b5212fb62dfea8d100f3efd1950f.pdf  for a wonderful series of maps that cover this campaign

Layers: Why a Military Simulation Is Like a Parfait

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Detailed military simulations and wargames are made up of layers1)Here is the obligatory link to Shrek and the layers, onions and parfait bit. by necessity. Layers keep simulation designers and users from being overwhelmed by oceans of data. In General Staff every scenario (battle) is made up of these layers (some are optional):

The Background Image. Ironically named because even though it’s underneath all the other layers it’s makes up most of what the user sees of the battlefield. However, the background image contains no data that is actually used by the computer; it is completely ‘eye candy’ for the user. That said, us humans get most of our data from looking at this map (we can make sense of the hills, roads, forests, rivers, etc.). But that’s not how computer vision works (see below).

The Background Image for the Antietam scenarios. Click to enlarge.

This map came from the Library of Congress (here). The Library of Congress is a great place to get royalty-free battlefield maps from American history. Personally, it’s exactly these old maps that inspired me to create General Staff. There is, however, one problem: these old maps are just not ‘GPS accurate’. That is to say, even though the General Staff Map Editor allows the user to directly import Google Maps elevation data, it won’t align properly with maps made over a hundred years ago without GPS data. That means the scenario designer will have to enter the elevation data by hand and not import it from satellite data.

The Terrain Layer. This layer is a visual display of what the computer ‘sees’ of the terrain: forests, water, fences, hedges, walls, swamp, mud, field, city, road, river, fortification, buildings (seven kinds), fords, and bridges.

The terrain layer for Antietam. Click to enlarge.

The Terrain Drawing tab (right). This is one of the tabs in the General Staff Map Editor (click here to go to the online Wiki for more detailed information). Click on the desired terrain type and then draw with either the mouse or a digitizing tablet and pen. I have absolutely no drawing abilities, but I’ve watched actual artists create a map using a digitizing tablet and pen in about 30 minutes. If you’re drawing a river, the harder you press with the digital pen the wider the river gets.

There are three ways you can input water and roads in the Map Editor: mouse, digitizing tablet and XAML code. For me, because I have very limited drawing abilities, I find using XAML code the easiest (below):

The Road Net Layer (optional). This image (below) was created in a paint program (PhotoShop, though any paint program that you’re comfortable with will work just fine). It was then imported into Inkscape (free download here) and exported as XAML.

The road net at Antietam. Click to enlarge.

The Water Layer (optional). Like the Road Net image (above) this was created in a paint program (PhotoShop). It was then imported into Inkscape (free download here) and exported as XAML.

Antietam water map. Click to enlarge.

The Elevation Layer. There are four ways to input elevation in the General Staff Map Editor: you can draw with the mouse, use a digitizing tablet and pen, input elevation data directly using Google Earth and directly importing a BMP image.

Antietam height map. Click to enlarge.

The Slope Layer. This layer shows the extrapolation of slopes from the elevation layer (above). Combined with the Background, and Elevation layer it can produce a dramatic 3D effect. See Trenton, below.

The Slope Layer for Antietam. Click to enlarge.

Blending Multiple Layers. This is a blend of the Background, Elevation, Terrain and Slope layers. The user can set the blend values (see screen shot from the Map Editor, right).

 

Antietam with background, elevation, slope and terrain blended. Click to enlarge.

The Places and Victory Points Layer. This layer allows you to set certain locations as Victory Points or Placenames. A Placename is a descriptive text placed on the map that has no importance to the simulation; e.g. labeling the Potomac River (below).

The Victory Point and Placenames Layer. Click to enlarge

The Units Layer. This is a visual representation of the current simulation state showing unit locations. This information may be filtered by Fog of War (FoW) and what units can observe other units (both friend and foe) using 3D LOS (see below):

The Units layer for Antietam. Note: reinforcements are displayed on this layer even though they won’t enter the scenario until later. This screen shot was taken from the Scenario Editor. Click to enlarge.

The Fog of War Layer. This layer is a visual representation of what can be observed from any point on the battlefield; in this case, the 3D LOS view from the Pry House (McClellan’s Headquarters at Antietam).

Antietam with complete Fog of War displayed for McClellan’s HQ at the Pry House. Click to enlarge.

The AI Layer. This layer is a visual representation of the output of a number of AI algorithms including Range of Influence (ROI), battle groups, and flank units. This is how the AI ‘sees’ the battlefield.

The AI Layer displays Red and Blue Range of Influence. Click to enlarge.

Trenton. I recently began working on a Trenton scenario. One of the best places to begin a search for a contemporary map of an American battle is the US Library of Congress. That is where I found the extraordinary campaign map for Trenton published in 1777.

From the US Library of Congress (published 1777, London). Click on the map to go to source.

From the above original map, Ed Kuhrt created an elevation or height map (see above) in PhotoShop. From that Elevation Layer we extrapolated the slopes and displayed them using an algorithm created by Andy O’Neill. When blended together the result is striking:

Screen shot of the Trenton map in the General Staff Map Editor. Note how the blending of the slope layer with the elevation and original background create a 3D effect. Click to enlarge.

References

References
↑1 Here is the obligatory link to Shrek and the layers, onions and parfait bit.

A Game of Birds & Wolves

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Commander Roberts going over the lessons learned from “The Game.” Photo from, “A Game of Birds and Wolves,” by Simon Parkin.

Simon Parkin’s A Game of Birds and Wolves: The Ingenious Young Women Whose Secret Board Game Helped Win World War II, tells the fascinating story of a wargame created during the height of the U-Boat Atlantic campaign to be used as a testbed for discovering new anti-submarine tactics. In early 1941, when German wolf packs were destroying Allied shipping at a devastating rate, British Naval Commander Gilbert Roberts was taken out of retirement and personally ordered by Winston Churchill to, “Find out what is happening and sink the U-boats.”

Roberts was given the top floor of the Western Approaches HQ in Liverpool and a small group of WRENs (Women’s Royal Naval Service) as assistants to invent tactics that would counter the enemy wolf packs. His project would be called the Western Approaches Tactical Unit (WATU). (The Western Approaches HQ in Liverpool is now a museum and I can’t wait to visit it when this pandemic is over and General Staff is finished.)

The WATU project – known simply as, “The Game,” – is not the first example of a wargame used as a testbed to discover and improve combat maneuvers. Indeed, Scotsman John Clerk, wrote, An Essay on Naval Tactics: Systematical and Historical in 1779 after using, “…a small number of models of ships which, when disposed in proper arrangement, gave most correct representations of battle fleets… and being easily moved and put into any relative position required, and thus permanently seen and well considered, every possible idea of a naval system could be discussed without the possibility of any dispute.” Using these models Clerk proposed the tactic of “cutting the line,” that Nelson employed at Trafalgar1)https://en.wikipedia.org/wiki/John_Clerk_of_Eldin. Nelson would quote from Clerk’s essay in his famous Trafalgar Memorandum.

When Roberts reported to Sir Percy Noble, commander of Western Approaches he explained that he intended to, “develop a game that would enable the British to understand why the U-boats were proving so successful in sea battles and facilitate the development of counter-tactics… The game would become the basis for a school, where those fighting at sea could be taught the tactics. With a few adjustments.. [the] wargame could be used for either analysis or training.”2)A Game of Birds and Wolves, p. 143 Not surprisingly, Roberts was met with skepticism and not a little bit of derision. As one who is constantly pitching the importance of wargames to the U. S. military I understand the uphill fight that Roberts was facing. British destroyer commanders definitely did not want to go to Liverpool to, “play a game.” But, since the orders had come directly from Churchill, Noble had little choice but to give Roberts the top floor of the Western Approaches HQ for his ‘game’. Roberts made a tactical mistake by referring to WATU’s ‘product’ (in modern bureaucratic parlance) as a ‘game’. I learned this early on in my career: never say the word ‘game’ if it can be avoided. Call what you’re working on a ‘simulation’. Chess is a game. Risk is a game. But I write simulations; and clearly what Roberts was working on was a simulation, too. (That said, the phrase, “game it out,” has now passed into the common idiom and is synonymous with ‘simulation’.)

WATU simulated Fog of War by requiring the users to view the board through peep holes cut in canvas drapes. Submarine tracks (see above) were drawn in green chalk which, apparently, was not visible from the other side of the canvas sheets. The photo shows British destroyer commanders playing, “The Game,” and learning from the simulation. Photo from, “A Game of Birds and Wolves.”

In order to simulate Fog of War Roberts invented a system in which the destroyer commanders would view the board from behind a canvas sheet; their view of the battle restricted by peep holes cut in the canvas. Furthermore, submarine tracks were drawn with green chalk on the floor (see above photo) which, somehow, became invisible when viewed from the other side of the canvas. Consequently, the destroyer commanders had only a restricted view of the battle around them and were completely in the dark as to the simulated U-boats positions.

When Roberts began his work nobody in the British Admiralty knew U-boat tactics. Indeed, the German U-boat commanders were creating their tactics on the fly often ignoring the Kriegsmarine’s Memorandum for Submarine Commanders to fire torpedoes at no closer than 1,000 meters. U-boat ace, Otto Kretschmer was the first to insist that the most efficient way to attack convoys was to slip inside the destroyer screen, launch torpedoes at a range of about 500 meters, submerge and wait for the convoy to pass over them to make his escape ‘out the back’ of the convoy. Interestingly, this was the same technique that I discovered playing Sierra On Line’s  Aces of the Deep.

One of the first scenarios that Roberts investigated using his new wargame was the battle of Convoy HG 76. This was a multi-day contest involving 32 merchant ships, 24 escorts and 12 U-boats. It was considered a great Allied victory because five U-boats were sank (though the Allies only knew of three at the time) and 30 merchant ships made it home safely. Assisted by WRENs Jean Laidlaw and Janet Okell, they replayed the historical situation hoping to understand Allied commander Captain Frederick John “Johnnie” Walker’s anti-submarine maneuver ‘Buttercup’. The Buttercup maneuver (named after Walker’s pet name for his wife) involved, “on the order Buttercup… all of the escort ships would turn outward from the convoy. They would accelerate to full speed while letting loose star shells. If a U-boat was sighted, Walker would then mount a dogged pursuit, often ordering up to six of the nine ships in his [escort] group to stay with the vessel until it was destroyed.”3)A Game of Birds and Wolves, p. 155

What confused Roberts was that the Allied merchant Annavore was torpedoed while in the center of the convoy. As he and the WRENs replayed the scenario they could not duplicate reality unless the U-boat had, “entered the columns of the convoy from behind. And it must have done so on the surface, where it was able to travel at a faster speed than the ships. By approaching from astern, where the lookouts rarely checked, the U-boat would be able to slip inside the convoy undetected, fire at close range, then submerge in order to get away.”4)The Game off Birds and Wolves. P. 158

Using the scenario of when the escorts actually sank a U-boat using the Buttercup maneuver it was determined that they had succeeded by only accidentally hitting a U-boat that was joining the attack on the convoy and not the actual U-boat who had made the attack that they were pursuing. This makes sense when you realize that the attacking U-boat had submerged immediately after the attack and was waiting for the remaining convoy to pass overhead while the escorts were running far outside the perimeter of the convoy looking for it.

In other words, Walker’s Buttercup maneuver was, in fact, a terrible anti-submarine tactic.

The ‘Raspberry Maneuver’, created from numerous runs of ‘The Game’ was determined to an effective anti-submarine tactic. Here it is drawn by Admiral Usborne. From the book, “A Game of Birds and Wolves.” Click to enlarge.

The first successful anti-submarine tactic to be invented using the Game as a test bed was, “Raspberry,” (so called by Wren Ladlaw as a ‘raspberry‘ to Hitler). As you can see from the above drawing, upon discovery of a U-boat or a torpedo hit, the escorts draw closer to the convoy, not the opposite as in Walker’s Buttercup maneuver. When Roberts and the WRENs ran a scenario for Western Approaches commander Noble and his staff, Noble – who at first was highly skeptical – was so impressed that he immediately sent a message to Churchill, “The first investigations have shown a cardinal error in anti-U-boat tactics. A new, immediate and concerted counter-attack will be signaled to the fleet within twenty-four hours.” 5)The Game of Birds and Wolves, p. 162 By summer of 1942, using these new maneuvers, U-boat losses had quadrupled. Eventually other anti-U-boat maneuvers were also developed by the WATU team and all Atlantic destroyer commanders were ordered to WATU to play, “The Game,” and learn the lessons.

Obviously, there were other improvements in anti-submarine warfare that also contributed to the Allies winning the Battle of the North Atlantic. Nonetheless, it is interesting to read about the proper application of simulations in wartime. I have long been an advocate of simulations to test, “what if” scenarios. Indeed, this has been the main focus of my professional career for thirty plus years. It’s still an uphill battle.

References

References
↑1 https://en.wikipedia.org/wiki/John_Clerk_of_Eldin
↑2 A Game of Birds and Wolves, p. 143
↑3 A Game of Birds and Wolves, p. 155
↑4 The Game off Birds and Wolves. P. 158
↑5 The Game of Birds and Wolves, p. 162