Diplomacy/Rules

Object of the game
The object of the game is to use your armies and fleets to conquer as much of Europe as you can. Specifically, you must capture and be in possession of at least 18 of the 34 nations or provinces on the map that contain supply centres - i.e. a simple majority - at the end of a year.

Quite often the game ends in a two-way, three-way, or even four-way draw. Draws are generally agreed upon by all players or are declared after a pre-set time limit has been reached with all surviving participants sharing in the win.

The game board
The board is divided into a large number of spaces, each identified by a name (often abbreviated to three letters). There are three types of space on the board: ocean or sea spaces, land spaces, and coastal land spaces. The type of space determines which units can occupy them.

34 of the land provinces are supply centers. Possession of these supply centers allows the powers who control them to raise and maintain armies and fleets. As they are also a central part of the game's victory conditions, they are the focus of much of the game's activity.

Each player is given three (save for Russia, which has four) home supply centers. 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.

Three specific coastal land spaces have multiple and separate coastlines: Spain, Bulgaria, and St. Petersburg. When occupying these coastal areas, fleets are considered to be stationed at one coast or the other, and cannot travel "through" a land space to get to the sea space off its opposite coast. They are readily identifiable by their specific coast names; for instance, Spain is marked with NC (North Coast) and SC (South Coast).

Other specific land spaces do allow fleets to travel through them from a sea space on one side to a sea space on the other. These land spaces are identified by the channel of water that goes through them. For example, a fleet could move from the Aegean Sea through Constantinople to the Black Sea in two moves, as long as those spaces were unoccupied.

Units
In Diplomacy, there are two types of units: Armies and Fleets. An army can travel in land spaces and coastal land spaces, and a fleet can travel in sea spaces and coastal land spaces.

Although all of the supply centers are on land, only seven supply centers are completely landlocked. Fleets are important to convoy armies across water, support coastal battles, create a blockade on sea spaces so that other fleets cannot expand, etc. Some countries can live without fleets since they are nearly landlocked geographically. Such countries include Russia, Germany, and especially Austria. On the other hand, English fleets are absolutely necessary since without them England cannot convoy armies to the mainland.

All units in Diplomacy move only one space at a time and only one unit may occupy any space at any time. The exception to this rule comes in the form of a successful convoy, where a convoyed army may travel multiple spaces depending on the length of the chain created by the convoying fleets. A convoyed army must embark from a coastal land province and land at a coastal land province.

Game Phases
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 arbitrator, 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).
 * Supply centers only change ownership if they're occupied at the end of Fall; they do not change ownership if a unit moves through them during the Spring, but leaves again in Fall.
 * 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.
 * Powers may not choose to disband below the number of supply centers in their possession, for this would allow players to replace units in the field with new units back home instantaneously. For instance, a player who has more armies than necessary and wants a fleet in order to capture a far-away supply center cannot simply disband an army and build a new fleet on a home supply center. (See "Movement" below).

Orders and the Movement Phase
There are four basic orders in Diplomacy: Hold, Attack, Support, and Convoy.

At each Movement Phase, players may order each unit either to hold its position, to attack (or move to) another province, or to support another unit (either to hold its position or to attack a province). Fleets may also be ordered to convoy armies across bodies of water to coastal provinces.

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/Fleet (Province that the unit is in) holds.

Example: Italy: Army Rome holds.

Attack/Move
This order moves the unit in one province to an adjacent province. Of course, armies cannot move into sea provinces, and fleets cannot move into landlocked provinces.

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.

Two units may not swap provinces, unless there is a convoy involved.

A move order is written as follows:

Army/Fleet (Province that the unit is in) to (destination province).

Examples:

Army Rome to Venice
 * Italy

Fleet Brest to English Channel
 * France

When the destination province is occupied by another unit, for instance:

Fleet Trieste holds
 * Austria-Hungary

Army Venice to Trieste
 * Italy

Army Venice and Fleet Trieste do not move, unless either are attacked or defended by stronger support.

When two units with equal support try to move into the same destination province, for instance:

Army Munich to Tyrolia
 * Germany

Army Venice to Tyrolia
 * Italy

Neither of the two units can go into Tyrolia. Army Venice will stay in Venice, and Army Munich will stay in Munich. Again, this is assuming that these two units are the only two units in this little battle, and that they have equal support for their moves.

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).

A country cannot dislodge or support the dislodgement of one of its own units, although if same country's units attempt to move into the same province with equal support, neither will succeed as normal.

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. An attack by a country on one of its own units also doesn't cut support.

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)

Example:

NB: Below are complete orders as submitted by all 7 Powers for the Fall 1907 campaign season of a made-up game to help you understand the intricacies of supporting and breaking support. Having a game map to look on with is highly recommended; the one provided at the top of this page is adequate.

We'll start with:


 * --Germany--
 * Army Ruhr to Holland 
 * Fleet Kiel supports Army Ruhr to Holland
 * Army Munich supports Army Ruhr to Holland

Note that in this case the order for Munich to support Ruhr into Holland would not work because Munich does not border Holland and thus cannot support Ruhr in (Munich could, however, support Ruhr if Ruhr were simply holding). The rule for supporting an attack is that a supporting unit must border the province being attacked, but need not border the attacker's province of origin (to support a unit to hold, however, the supporting unit must border the supported unit). Essentially, the supporting unit must border the destination of the supported unit, whether it is its own province or a new province entirely. In sum, Ruhr is actually attacking Holland with the support of only one unit (Fleet Kiel).


 * Army Prussia supports Army Silesia
 * Army Silesia supports Army Prussia

Here, Army Prussia is supported by one unit, and Army Silesia is supported by one unit. The last two moves are legal, and this method of double-support is helpful when there are two units that both could be attacked and dislodged. Of course, if both units are attacked, the support fails.


 * --England--
 * Army London to Holland
 * Fleet North Sea convoys Army London to Holland (<-- a convoy)
 * Fleet Heligoland Bight supports Army London to Holland

Note that the convoying fleet is not considered to be giving support, so Army London actually has support from only one unit: Fleet Heligoland-Bight.


 * Army Denmark to Kiel

Here England interferes with Germany's plans (see Germany, above) by attacking Kiel with Army Denmark. This cuts the support of Fleet Kiel to Army Ruhr, thereby leaving Army Ruhr's attack on Holland unsupported.

Army London, on the other hand, (see above) is supported in its attack on Holland by one unit (Fleet Heligoland-Bight), thereby enabling Army London to be convoyed successfully into Holland, as long as Fleet North Sea is not dislodged during the convoy.


 * Army Picardy to Brest
 * Fleet Mid-Atlantic Ocean supports Army Picardy to Brest
 * Fleet English Channel supports Army Picardy to Brest

Here Army Picardy is supported by both Fleet Mid-Atlantic Ocean and Fleet English Channel to move into Brest. Unless the French successfully defend it, England will also take Brest.

--France--


 * Fleet Gascony to Mid-Atlantic Ocean
 * Fleet Irish Sea to English Channel

Fleet Gascony and Fleet Irish Sea cut the support by Fleet Mid-Atlantic Ocean and Fleet English Channel for England's Army Picardy (see England, above). Therefore, Army Picardy is now attacking Brest unsupported.


 * Fleet Brest holds
 * Army Paris supports Fleet Brest

Army Paris supports Fleet Brest, and so Army Picardy’s now unsupported attempt to move into Brest fails.


 * Army Burgundy to Ruhr

Army Burgundy does not successfully move into Ruhr because Army Ruhr’s move to Holland failed (see Germany and England, above).

--Russia--

Fleet Sevastopol holds Army Moscow supports Fleet Sevastopol

Fleet Sevastopol is supported by Army Moscow.

Fleet St. Petersburg (North Coast) to Norway Army Finland supports Fleet St. Petersburg (North Coast) to Norway

Norway is not occupied, so Russia takes it immediately.

Army Livonia to Prussia

Unsupported Army Livonia attempts to move into Prussia, but since Army Prussia is supported by Army Silesia (see Germany, above), the attack is not successful.

--Austria-Hungary--

Army Ukraine supports Fleet Sevastopol

Army Ukraine supports Fleet Sevastopol, so there are now two units supporting (see Russia, above). In fact, international support is necessary in alliances, whether supporting each other in defence or to attack another Power.

Fleet Trieste holds Army Budapest supports Fleet Trieste Army Vienna supports Fleet Trieste

There are two units supporting Fleet Trieste: Army Budapest and Army Vienna.

--Turkey--

Army Galicia to Ukraine

Army Galicia cuts the Austrian support to Sevastopol, thereby decreasing the support to Sevastopol by one unit (see Austria and Russia, above).

Fleet Black Sea to Sevastopol Army Armenia supports Fleet Black Sea to Sevastopol Army Rumania supports Fleet Black Sea to Sevastopol

Now, since Fleet Black Sea is supported by two units into Sevastopol, Fleet Black Sea moves into Sevastopol, and Fleet Sevastopol has to be disbanded or retreat. A retreating fleet that is displaced by another force can only retreat into a movable space (i.e. a sea or coastal province that is vacant) which may not be the same space that was previously occupied by the displacing unit.

Since Fleet Sevastopol has nowhere to retreat, it disbands automatically.

--Italy--

Army Apulia to Trieste Fleet Adriatic Sea convoys Army Apulia to Trieste Army Venezia supports Army Apulia to Trieste Fleet Albania supports Army Apulia to Trieste

There are two units supporting Army Apulia into Trieste, but since Fleet Trieste is supported by two units (see Austria-Hungary, above), the attack bounces.

Finally note that the orders for both the army being convoyed and the fleet doing the convoying must use the proper protocol and fully identify the units involved in the convoy. This is a complex manoeuver and becomes more complex if it involves units controlled by more than one power.

Convoy
This move is used to transfer army units across sea spaces, or to move large distances in one move. Only armies may be convoyed, and only fleets may convoy.

Let us say, for instance, that in Fall 1901 England has the following position: Army Yorkshire Fleet North Sea Fleet English Channel

A convoy order would be:

--England-- Army Yorkshire to Norway Fleet North Sea convoys Army Yorkshire to Norway

Army Yorkshire will move to Norway, unless another unit should prevent this process by dislodging or destroying the convoying fleet. If a convoy order fails and the convoyed piece could not ordinarily move there without the convoy, the convoyed army unit holds.

The unit being convoyed can be supported into its destination space by any other units that border the destination space, just like any other support. However, if the convoying fleet is dislodged, it cannot convoy the unit and the entire move will fail. Note that convoys are not "broken" as easily as support; a convoying fleet that is attacked but not dislodged will successfully carry out its convoy order.

Convoying fleets can be supported to prevent them from being dislodged or destroyed. Convoying fleets cannot perform any other order.

A fleet on a coastal space may not convoy.

If an army can arrive to its destination either by land or convoy, convoy is used if at least one of the convoying fleets belongs to the army's owner, or if army's owner specified "via convoy" on the army's move order; otherwise, land route is used.

If several fleets are convoying an army so that it can take multiple routes to its destination, convoy succeeds as long as at least one convoy route remains open.

Abbreviation of Orders
Most orders are not written out as lengthily as they are in our examples. For instance, here is a set of Russia's moves written in an abbreviated form:

A Mos H A War-Gal A Bud S A War-Gal A Sev-Ank F Bla C A Sev-Ank

Abbreviations of most provinces are written as the first three letters of the name; for instance, Bal for Baltic Sea, Lon for London, and so on. There are exceptions for the provinces whose names begin with "Nor", as there are several; many use the following: Nth for the North Sea, NAt or NAO for the North Atlantic Ocean, NAf for North Africa, Nwg for the Norwegian Sea, Nwy for Norway. Additionally, the Tyrrhenian Sea is abbreviated as TyS or Tyh to avoid conflict with Tyrolia (Tyr).