The object of the game is to use your armies to conquer as much of the map. Specifically, you must
capture and be in possession of at least 13 of the 25 districts that contain supply centres - i.e. a simple majority - at the end of a year. One of the 13 districts you must possess in order to win is SIN.
Each player is given four home supply centers (B, G2, M1 and M3). These spaces are the starting point for their owning power's initial forces. The players can then build new units at these home supply centers as they capture further supply centers. New units can only be built on a power's home supply centers. If a power loses all of its home supply centers it may continue to play; however, it may not build new units until it has recaptured at least one of its home supply centers.
All units in Diplomacy move only one space at a time and only one unit may occupy any space at any time.
Gameplay begins in the year 1901, and there are two
moves or
Movement Phases per year, one in
Spring, and one in
Fall.
- Before each move, orders for all of a player's units are written in secret and submitted to the Hal, who then makes all necessary adjustments to the board/map.
- If a unit is dislodged as a result of the move (overpowered by other players), the player must submit Retreat Phase orders that the unit either be retreated to an unoccupied adjacent province or else disbanded and removed from play.
- A unit may not retreat to the province from where the dislodging unit came or to an "embattled" province, meaning one left vacant by a bounce/standoff that turn.
- If a unit has no legal retreats, or it attempts to retreat to the same province as another retreating unit, it is disbanded.
- After the Fall move and the subsequent Retreat Phase, and before the next year begins, a tally is made of the total number of supply centers controlled by each Power. A Power controls a supply center if 1) it has a unit (army or fleet) occupying the province with that supply center or 2) the province with the supply center is unoccupied and the Power was the last to occupy that province at the end of a year. Each supply center can support one military unit, so Powers that have gained supply centers over the course of the year can build new units. New units may be created at any of the player's unoccupied home supply centers, but only at these centers, and at most one unit per center. For this reason, no more than 3 new units per player can ever be created at a time (except in the case of Russia, which has 4 home supply centers).
- On the other hand, if a Power has more units than supply centers at the end of the year, then it must disband units of its choice until it has equal numbers of units and supply centers.
There are three valid orders you can give for your units: hold, attack, and support.
Hold
This is the default for all units (what they will do if not given any other orders). The unit will stay in its position, and will not move, support, convoy, or do anything. Holding units can be supported by units in neighboring provinces or be attacked by foreign units. If the attacking unit has more units supporting it than the holding unit, the holding unit is ousted from that province and must either retreat or disband (see above).
A hold order is written as follows:
Army (Province that the unit is in) holds.
Example: Zorbees: Army ZG2 holds
Attack/Move
This order moves the unit in one province to an adjacent province.
A unit may not move into a province held by another unit unless it has
support. As units may be supported either in attacking a province or in holding a province,
the attacking unit must have more support than the defending unit if the attack is to be successful. If the attack is not successful, the attacking unit does not move anywhere.
A move order is written as follows:
Army/Fleet (Province that the unit is in) to (destination province).
Examples: Zorbees: Army ZM3 to ZM5
Support
Support is the trickiest aspect of the rules, and the most important of the game. Support may involve cooperation between two (or more) powers, and is the only way to make forward progress through enemy territory (unless you can convince the enemy to let you in). Simply put,
more support defeats less support.
The support order is given in reference to another unit's move. That other unit's move must be to a province into which the supporting unit could otherwise move. Support may also be given to a unit holding its position. In addition, units giving support can themselves be supported in their holding position.
Support is a unit's sole action for a given move, and supporting units remain where they are (unless they are attacked by greater support and have to retreat or disband during the retreat phase).
Cutting Support: If the supporting unit is attacked during the turn by some other unit, its support is cut. In effect, the support order becomes a hold order, as the unit must defend its province against the attack. Note that a unit occupying the province into which the support is directed cannot cut support, unless its attack successfully dislodges the supporting unit.
Support orders are written thus:
Army/Fleet (Space that the supporting unit is in) supports Army/Fleet (Space that the supported unit is in) to (destination of supported unit)
or
Army/Fleet (Space that the supporting unit is in) supports Army/Fleet (Space that the supported unit is holding)
Examples:
Zorbees: Army ZM3 to ZM5
Army ZM6 supports Army ZM3 to ZM5