Army of the Potomac: Fair Oaks/ Seven Pines’ the McClellan Gambit 

Introduction 

Scenario design is often an assumed or lesser recognized element of game design. I often use the opening scenario set up to cause players to behave more historically without any special rules. This usually results in someone telling me that they found a trick that was not seen during playtesting. Back when we used to hold a Pacific War tournament at the World Boardgaming Championships that were several scenarios where if the offensive player is far less aggressive than their historical counterparts a draw or a ‘cheap’ victory could be achieved by the reaction player. Mea Culpa, but this was intentional as part of the history lesson is when you are cast in the role of the aggressor, you better be aggressive else things can go sideways on you. 

In Army of the Potomac there are several situations where the side launching the offensive, needs to act like they mean it, else defeat is likely. While the Grand Tactical level in 19th century warfare appropriately features maneuver, at some point it’s a bloody Civil War and you have to get about the business of fighting, something that seems to be forgotten by those who get upset about having their pieces removed from the mapboard. To reiterate, it’s a bloody Civil War where the newspapers used entire editions just to list the names of the fallen. In the game’s Playbook I suggest that if you are new to the system or looking for a quick opening scenario, play Fair Oaks/ Seven Pines (page 6) as its only two turns in length with very few units. For me average playing time is around 15 minutes. You can watch two friends of mine (Jeff Frye and Alan Sawyer) play out this scenario on a live stream with commentary. 

As I have written in my book, Wargames According to Mark when I am designing a wargame I consider kinetic and psychological history that are both featured in this short opening scenario. The kinetic history is that all of the CSA and USA units are in the correct locations with limited reinforcements due to the Chickahominy River’s flood conditions. That is the easy part, but the more interesting consideration was the mindsets of the two commanders, Generals Joseph Johnston (CSA) and George McClellan (USA). McClellan was as always in a defensive state of mind but had left himself vulnerable to an attack by allowing his army to be bisected by a river in flood stage. 

Johnston was also in a defensive state of mind, but he was getting strong pressure from President Davis and his then chief military advisor General Robert E. Lee, both of whom due to their close proximity to the battle lines (only 5 miles or so from Richmond) could ‘consult’ with Johnston who jealously guarded his command prerogatives. What this meant in practice is Johnston would not share his plans or intentions with his leadership while they were actively trying to look over his shoulder. The situation was further exacerbated by General Lee in a vain attempt to get Johnston to attack began to run a ‘secret’ parallel set of operations with Stonewall Jackson in the Valley. The net effect of all of this was Johnston planned then cancelled one attack then reluctantly conducted the one covered in this scenario. 

 To subtly show two generals who more or less do not want to fight, I have created the circumstances whereby a poorly conducted CSA attack will allow for a Union ‘Fabian’ style victory. This article is to forewarn you Joe Johnston fans out there that if you act like JJ, you will give McClellan the opportunity to be McClellan. Have fun storming the castle! 

Historical Situation 

One of the salient features of McClellan’s Peninsula campaign is that once the Army of the Potomac had advanced to the Richmond environs its positions were bisected by the Chickahominy river. On the occasion of the Seven Days Battles the bulk of the Union forces were south of the river and earlier on May 31st they were north of the river. On both occasions the CSA, first under Joe Johnston (Fair Oaks/ Seven Pines) and later under Robert E. Lee (Seven Days Battles, page 9) attempted to exploit McClellan’s tactical mistakes by eliminating the weaker portion of the Union army. 

On May 29th Joe Johnston was setting up an attack against the Union position on the north side of the river, but heavy rains initially delayed and ultimately cancelled this attack. The rains put the Chickahominy river into flood stage, washing away several of the bridges that connected the two halves of the Union army. Johnston then revised his plans, which he poorly communicated to his subordinates or superiors, to attack the exposed Union IVth Corps positions at the Fair Oaks railroad station and the nearby Seven Pines crossroad. 

The Union positions had no intrinsic military value so it was entirely feasible that the Union IVth Corps could easily have withdrawn if it perceived that they were facing superior forces. As it turned out the Union forces stood their ground and were reinforced initially by the Union IIIrd Corps and later in the day by the IInd Corps led by ‘Bull’ Sumner who braved an unstable bridge to enter the fight. 

Both scenarios are in my Army of the Potomac design. This article will examine the possible path not taken by McClellan whereby the Union withdraws instead of fighting. 

Fair Oaks/ Seven Pines Scenario 

In the Army of the Potomac Fair Oaks/ Seven Pines scenario there is something that I will call the McClellan gambit, whereby the Union attempts to withdraw the exposed Union IVth Corps (Casey and Couch Divisions) beyond Johnston’s command range so they cannot be attacked. I saw this possible strategy the first time I set up the scenario to test it. While I considered putting in a strategic victory condition to cause the Union to stand their ground, I wanted to capture the psychological mindset of two defensive minded generals, and I left this historical path not taken in the scenario without special rules. 

The next decision was who would win ties if there was no battle? My view is that if the Union had retreated, the CSA would not have gained any military advantage. The bulk of the Union forces were north of the river, and an aggressive advance would expose the CSA river flank to a counterattack once the river level fell. Therefore, I decided that the onus of attack was on the CSA, with ties going to the Union forces, to include a 0-0 tie, forcing you to commit to an attack that you do not want to conduct. 

However, if ties go to the Union would the game systems make for an interesting match. As it turns out Johnston’s plan, if well executed, which it was not, would have prevented the withdrawal of all of the Union forces, accomplishing his objective to defeat the Union army in detail. This is the situation that will confront both sides if you play the Fair Oaks/ Seven Pines scenario. 

CSA Refutation of the McClellan Gambit 

First off, what is the McClellan gambit? Basically, the exposed Union forces attempt to withdraw outside of Johnston’s command range without engaging in combat. If the Union accomplishes this, they will achieve a 0-0 VP tie, which is a Union ‘Fabian tactical’ victory. As I stated earlier this was intentional on my part, as a failure to accomplish the attack’s objective would be a defeat. I have positioned the opposing HQs in such a manner that their command ranges only overlap over the immediate area of the battlefield. There is a solution to this gambit that is easily refuted if the CSA uses the historic attack plan or the Union decides to hold their ground. 

Spoiler Alert: Do NOT read any further if you want to figure this out on your own, else continue. 

Note: this article is using the penultimate playtest maps and counters (I wrote it last December), hence any discrepancies or the artist’s obvious purple alignment hex are not on the final published maps. 

CSA Grand Tactical Maneuvers 

If you read my C3i #38 Clio’s corner article that is reprised in the Army of the Potomac Playbook you will be exposed to Jomini’s definition of the Grand Tactical level of warfare that states, “the art of making good combinations preliminary to battle, as well as during their progress.” So, what is built into the DNA of this design is maneuver whose aim is to create advantage (or hopefully significant advantage) in the attacks that follow. Johnston’s attack plan is a classic double envelopment that if executed properly will ensnare the Union IVth Corps (Casey and Couch Divisions). Casey is in a small redoubt with a battery of guns with Couch in close support. The Union IVth Corps is backed up by the IIIrd Corps, with the remainder of the Union army on the other side of the Chickahominy River currently at flood stage. 

The CSA is the first player in the scenario and should initiate their attack by advancing Smith’s Division (Whiting a) to turn the Union right flank. 

CSA 1st Move: Whiting a [Smith] (C4323) moves via extended march to hex C4720 and remains in Maneuver formation. The McClellan Gambit requires the USA to withdraw either Couch or Casey with their first move. As Couch is on a road and Casey is in a non-road defensible position, we will assume that the Union withdraws Couch [IV] (C4922) toward the McClellan HQ outside of Johnston’s HQ range. 

CSA 2nd Move: Whiting a [Smith] moves to hex C4822 (2 hex move) where it changes to battle formation due to Casey’s ZOI (C4824). 

If Casey now attempts to retire, any movement will force him to cease his move after one hex when he is forced to change to battle formation (remove Fieldwork). Depending on where Casey moves you either use Whiting a [Smith] to move into Casey’s ZOC or in the more likely case Casey moves away from Whiting a [Smith] toward McClellan’s HQ. 

CSA 3rd Move: Longstreet a [Longstreet] (F1502) moves to C5026 via normal march then changes to battle formation. 

CSA 4th Move: No matter where Casey moved either CSA unit, Whiting a [Smith] or Longstreet a [Longstreet], advance one hex into Casey’s ZOC, ending his movement with subsequent CSA moves creating three Division attacks by Longstreet, Whiting, and DH Hill’s Divisions against Casey’s Division to gain a 1VP Generalship advantage. 

This set of moves mirrors the historical plan and prevents the Union from escaping the CSA offensive. As stated, the attempt is to eliminate Casey. Now under normal circumstances, especially when using the resurrected Rebel Fury Flank attack rule (page 3 Playbook), without artillery support is a tactical position 6 versus 3 attack (flank attacks prevent defensive artillery support and only +1 terrain benefit) yielding the probability for a successful attack of 76% and two attacks is 94% with three attacks for completeness 98%. However, this is the spring of 1862, and Johnston has not told anyone, except Longstreet, what the attack plan is, so the scenario rules prohibit attack support and flank attacks, so you only benefit from the Corps/Division integrity bonus. 

These attacks will likely be tactical position 4 versus 9 (assumes Union uses their limited defensive artillery support) that collectively over three attacks with the Rebel high quality units yields an overall 37% chance of success. While those are not great odds it does accurately reflect the battle conditions on May 31, 1862. Regardless of the overall attack results the Union will have exhausted their artillery ammunition prior to the PM turn. 

Note: For excruciating detail on the Civil War Heritage combat system go to: https://insidegmt.com/rebel-fury-advanced-assault-tactics/ 

Union Response 

Once the CSA successfully begins their turning movement the Union player needs to decide what to do next. The Union forces main advantage in this battle is that the CSA command structure is not coordinating well and inexplicitly Johnston has not deployed many guns to support the attack. Consequently, the Union has artillery superiority but limited ammunition as the majority of the ammunition wagons are on the wrong side of the flooded river. 

The basic response is to prevent the double envelopment by bringing the Union III^rd Corps forward to guard the IV^th Corps flanks and hold until the afternoon turn when ‘Bull’ Sumner in perhaps his greatest Civil War moment takes his II^nd Corps across collapsing pontoon bridges to save the day. The major Union decision is how much ammunition to use to maintain their defenses while leaving sufficient ammunition for any afternoon counterattacks to rectify a losing situation. As the Union tactics are fairly obvious, I have written solitaire guidelines for them so you can play the game right out of the box. 

Conclusion

The main point is the CSA can force the Union to fight whether they want to or not thereby refuting the McClellan Gambit. Based on playtesting the scenario is usually a Union victory by about 1 VP, mostly driven by how well Casey defends against the initial CSA attacks and how the limited Union artillery ammunition is used. The scenario usually follows one of three possible paths: 

1. Casey and one CSA division are blown with the PM turn deciding the outcome. Broadly this is the historical situation. 

2. Casey is blown and any failed CSA attacks are retreats, leading to a Union PM counterattack to save the day. 

3. Casey stands, multiple CSA units are blown, pretty much game over. 

That said, I assessed the historical CSA chances for success as historically low, so to avoid having anyone see you cry, play it solitaire. If it’s a learning scenario or a quick session I would suggest either bidding VPs for balance, using the included optional artillery ammunition variant, or preferably playing it multiple times and changing sides with the overall performance determining the match winner. 

Historically, the CSA attacked in unsupported waves with the Union IVth Corps taking a beating (case 1 above) that the arrival of Union reinforcements rectified with darkness ending the battle. The most significant outcome of the battle was that Joe Johnston was wounded and on June 1st, 1862, General Robert E. Lee took command of what was to become the Army of Northern Virginia. 

I hope Army of the Potomac owners take the time to check out this fun and incredibly short scenario before they dive into the larger scenarios, particularly my favorite in this volume, Cold Harbor. 

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