This is a 2-player game similar to the 2-man game in the Rulebook (see Rule XIV.2). There are two sides:
The Allies (England, France, and Russia)
The Central Powers (Austria, Germany, and Turkey)
Italy is neutral and Italian territory (Pie-Ven-Rom-Nap-Tus-Apu) may not be entered. See the last paragraph of Rule XIV.2 for the way in which supply centers and adjustments are computed.
The game begins in Spring 1914. After that, the following schedule is observed:
Spring 1915: A coin is tossed. Italy joins the winner and Italian units may now move the same season.
Spring 1917: The United States enters the war on the side of the Allies. Two American armies, and only two, may now appear on the board. They are maintained by two supply centers off the board; if forcibly disbanded (annihilated) either or both may be replaced (see below for how they come onto the board). The American armies operate as French units and any supply centers they capture are owned by France.
In Spring 1917, the American armies may be ordered into any two of the spaces bordering Nat, Iri, or Mid, provided that no Central Power’s fleet blocks the way from the western edge of the board to that province. These movement orders may be supported by any unit already on the board. American armies may also move onto the board in later seasons.
Fall 1918: The Russian Revolution occurs and the Russian Civil War breaks out. In this and all following seasons, Russia goes into civil disorder (see Rule XIV.3).
The victory criterion for “The Great War” is essentially the same as for the two-player game in the Rulebook. It is 24 units actually on the board, but also requires ownership of at least 24 supply centers.