Let's start with the premise that Union leaders simply cannot afford to operate more than 15 hexes from a supply source (i.e. Primary Supply Range) for these reason:
- Disorganization: Leaders beyond Primary Supply range become disorganized. It is not reasonable to expect successful attacks by disorganized Union leaders against organized Confederates which are often doubled or tripled by entrenchment.
- Attrition: Losses to attrition count in the manpower calculation toward victory points. It is unsustainable for the Union to lose 1 manpower per leader to attrition every turn without comparable loss by the Confederates.
- Reinforcements: Leaders must be organized to receive reinforcements. Since the Supply Phase comes before the Reinforcement Phase, no leader beyond Primary can take on reinforcements.
- RR Destruction: A leader must be organized to start and finish RR destruction during the game (and must spend one entire turn in place). At the end of the game, a Union leader can destroy a RR line as long as its combat value is 4 or more and it is within Primary supply range.
Union RR stations north of the Rapidan River are supply sources only for the first three turns of the game, unless the Union player garrisons the line with leaders totaling 6 or more combat value. But an "inland" Union offensive is unsustainable in any case because a 15-hex supply line from Rapidan Station only reaches south to the 2200 hex row. Eventully the Union must switch to coastal supply bases to advance further south.
Belle Plain is the coastal supply base at the start of the game. Primary range reaches west to the Wilderness area and south to Milford Station (2312). Note that this southern reach is limited because supply lines can't cross the unbridged Rappahannock south of Belle Plain.
The Union will be able to build three Supply Bases during the game. These can be completed on turns 3, 5, and 7. (Technically also on turn 9, but that's the end of the game.)
On turn 3 a supply base can be ready at Hazlewood or Port Royal on the Rappahannock. On turn 5 at White House landing on the Pamunkey. Note that the 15-hex inland extent of the latter only covers the east branch of the double railroad between Richmond and Hanover Junction. Don't wait too long to destroy the Virginia Central north of Hanover.
The turn 7 supply base is extraneous because it can't enlarge on the supply coverage of the previously placed bases. One possibility is to build it on the James River to prepare for a sea move to threaten Petersburg.
Remember, it is not the supply base that is the source, its the depot. Each Union corps has its own depot as its sole source of supply. Once you shift a depot to a new base, it commits the associated corps to that base's specific 15-hex Primary range. There is very little overlap between the Rappahannock and the Pamunkey. Timing the change of base takes some planning.
The Shenandoah Valley can theoretically bring in 5 victory points, but this is a pure fluke if it happens. If the Union can gain initiative in the valley the Confederates must remove 4 manpower points from the board. The CSA would do that only to prevent a Union automatic victory, so these VPs are most likely not going to arrive.
There are 31 Confederate RR station "burn points" on the map. If the US burns them all, that yields 15 VPs. The 7 points of RR stations south of the Appomattox are likely out of reach, and burning all the others will be contested by the Confederate forces. That brings the maximum points for RR station burning to 12 VPs, with a realistic expection of 6 to 10 points.
For RR destruction, the two "easy" ones are worth 7 points total. Note that the Virginia Central (6 VP) should be cut by a leader drawing supplies from Hazlewood (or adjacent base): the rail line from Hanover Junction to Noel's Turnout is within primary supply range. The York River RR is worth only 1 VP, but should be an easy pickup at the end of the game.
The rail lines south of the Appomattox - Weldon (14), Southside (6), Norfolk & Petersburg (3) - are within primary supply range of Bermuda Hundred (only).
That leaves the Richmond & Danville RR (12 VP). Unfortunately none of it is within 15 hexes of White House landing. Some of it is within primary supply range of Bermuda Hundred, but is the Army of the James up to the task of arriving there by the end of the game with a valid supply line?
Union cavalry can draw supply from ANY depot. So if there is a supply line available from Bermuda Hundred, Sheridan (after building up to at least four manpower) can threaten the Richmond & Danville RR, depending on the amount of Confederate cavalry remaining to chase after him.
- No points for the Shenandoah Valley.
- 12 points for burning all stations north of the Appomattox River.
- 7 points for destroying the Virginia Central RR and York River RR.
- This total (19 VPs) = Confederate Marginal Victory.
Union victory levels are attainable through comparative manpower losses, calculated as (CSA losses x 1.5) minus (USA losses). The Union needs to keep manpower losses increasing, steadily and equally - the higher the better.
If manpower losses are:
14 per side = Union marginal victory.
44 per side = Union substantive.
74 per side = Union decisive.
A substantive or decisive victory seems impossible through manpower losses alone. These would necessitate the destruction of either the Weldon RR or Richmond & Danville RR.
Confederate Supply Notes
The CSA does not have to worry much about supply sources until RR Destruction markers appear on the map. A RR station can't be a supply source if its RR line is cut off from all city hexes. Note that Richmond (or Manchester) is the ultimate supply source, not the map edge.
It may seem strange that Confederate cities can supply the ANV even if completely cut off. We must assume that enough supplies had been stockpiled in the cities to maintain the troops for the six-week time frame of the game.
There is no incentive for the Confederates to fight the Army of the Potomac, given the VP disadvantage for Manpower losses.
Automatic Union Victory
Can the Union simply ignore all other VP sources and race for Richmond as fast as possible for an automatic victory? Assuming forced marches and/or secondary supply line penalties, they will arrive before Richmond disorganized. Do they attack right away, or delay to get organized first?
Once the CSA player sniffs out Union intentions, he will be racing his own forces to Richmond, too, and digging in. Since the Union requires a primary (15-hex) supply line to Richmond for automatic victory, the CSA will likely be trying to disrupt this with careful placement of entrenched cavalry or counter-attacks in the city itself.