Across the Potomac, the issue game in Command No. 30, is a variation of designer Ben Knight's popular Victory in Normandy system.
The salient aspects of Knight's system are daily turns, a very restricted number of "Command Points" and a D10 "firepower-based" combat resolution system.
The daily turns mean that his games have a very large number of turns, compared to what's typically found in wargames. While many other wargames have 10 turns or so, and a few may have up to 20, Across the Potomac has up to 50, covering the period 3 June to 22 July 1863.
Mitigating the large number of turns is the very restricted amount a player can do in each of them, and Across the Potomac is one of the most restricted in the entire series. Essentially units can only move or attack if activated with a "command point." The Union player has just one command point at start (to share among at least a dozen eligible hexes of units). Once Meade replaces Hooker (driven by certain events) the union player gains a second CP. The Union player gains another CP once the Confederates enter northern territory. The Confederates start with two CP and gain a third when they cross into the North as well. At start they only have 10 hexes of units vying for the CPs. This simple differential allocation of a limited resource easily hands the game initiative to the Confederates, and elegantly captures the Napoleonic maxim that mass times speed equals impact. Although seriously outnumbered, it's the rebels who will be dictating the action.
Finally, the combat system is a variation on the line-them-up-and-fire system seen in such disparate games as Alexandros, Victory in the Pacific and Columbia's Block games. Here the system uses a 10-sided die. With the majority of the units having less than a 50% chance of a hit, multi-day battle are likely.
One unusual aspect of the game is the optional double-blind movement system. While slowing the game somewhat, it's an interesting exercise that tends to help the Rebels even more, as the Federals struggle to use their limited CPs to react to multiple threats. The low counter density allows the double blind system to work better here than it did in most land combat games where it's been tried.
Physically the game is fairly standard XTR fare, with the large 5/8-inch iconic counters often used in Command Magazine. The game is simpler than the 14-page rule book implies. It takes less than 15 minutes to set up and the game is easily playable in an evening double blind. It may be possible to play a two-game match in an evening if you play on one map.
That map represents a transition for XTR. For several years up to that point Command Magazine maps had been done by Mark Simonitch (perhaps best known now for the map used in Europe Engulfed) which were attractive, functional yet understated. With Across the Potomac XTR switches to maps done by Beth Queman. While certainly still functional (by which I mean no terrain ambiguities and everything affecting play is clear and legible) the map is less attractive than Simonith's work in my opinion. The colors are strong and the artwork is very obviously computer generated. No one will be tempted to frame it.
(Yes) for Wargamers: A good treatment of the campaign at a level not usually seen. Allows a nervy Federal to try Hooker's "trading queens" strategy of reacting to a Rebel invasion by invading the South.
(conditional Yes) for Collectors: One of the very few double-blind land warfare games.
(conditional No) for Eurogamers: Less "fiddley" than usual for a hex-and-counter wargame with intuitive game mechanics. If interested in the topic, this might be a good game to check out.