You are randomly assigned a great European power. This is the only random element of the game. As you can see, the powers are not equal.
The map is divided into land and sea territories. These are traditionally abbreviated with 3 letters. The seas are uppercase (e.g. ION—Ionian Sea), while lands are written in lowercase (e.g. Bel—Belgium). Switzerland is unpassable. Some of the land territories contain Supply Centers, which are marked with a circle. There 36 of these. As soon as someone owns 18 (50%+1), they win the game. The SCs that are colored on the above map are a power’s Home Supply Centers. These have a special meaning for the power they originally belong to (for others, they are the same as neutral SCs).
There are two types of units: armies and fleets. The fleets can only occupy sea and coastal territories. Armies can only occupy land territories. A power can posses as many units as they own supply centers. All units are of equal strength.
A game year is consists of five phases, some of which may be skipped if there is nothing to be done:
1) Spring moves (AKA Diplomacy phase)
2) Spring retreats
3) Fall moves (AKA Diplomacy phase)
4) Fall retreats
5) Builds/Disbands
During a Moves/Diplomacy phase the players submit orders for every unit they own. Once all orders are submitted, they are evaluated simultaneously. There are 4 types of orders:
1) Hold—The unit does nothing, just holds its position.
This order is traditionally written as “A Ven Holds” (army in Venice holds) or “F BLA H” (fleet in Black Sea holds).
2) Move—The unit attempts to move to an adjacent territory.
This order is traditionally written as “A Ber-Mun” (army Berlin moves to Munich) or “F Lon-ENG” (fleet in London moves to the English Channel).
In a basic case where no other units attempt to move to a territory, the move succeeds, and in the next phase that unit is in the new territory. If a unit attempts to move to a territory occupied by another unit (friendly or not), that move will fail, unless the other unit moved out. If two units attempt to move to the same territory, neither move succeeds. This is known as a bounce. As an example, let’s assume there are units in Greece (Gre), Serbia (Ser) and Romania (Rum), while Bulgaria (Bul) is vacant.
A) A Ser-Bul, A Rum-Bul, A Gre-Bul; No moves succeed, everything remains as is entering the next phase.
B) A Ser Holds, A Gre-Ser, A Rum-Bul; Greece army doesn’t enter Serbia, Romanian army moves to Bulgaria.
C) A Ser-Bul, A Rum-Bul, A Gre-Ser; Serbia and Romania bounce in Bulgaria, meaning Serbia is not vacant. That means the Gre-Ser move fails as well, no one moves in the end.
D) A Ser-Gre, A Gre-Ser, A Rum-Ser; Serbia and Greece attack each other, nothing happens. Serbia is still occupied so Romania can’t move into it.
Note: It is possible for two armies (e.g. in Gre and Rum) to defend three territories (e.g. Gre,Bul,Rum) by bouncing themselves.
Note: When it comes to coastal territories (i.e. a land bordering a sea) that can be occupied by both armies and fleets, same rules apply to both.
Now the question is how to defeat an enemy unit. The third order type is:
3) Support—The unit helps another unit move/hold.
This order is traditionally written as “A Ser S Gre-Bul” (Army in Serbia supports the move to Bulgaria from Greece) or “A Rum S Bul Hold” (Army in Romania supports the Bulgarian unit’s hold).
A unit can offer support in any territory it could move to (e.g. Greece can’t support Ser-Rum, because it cannot move to Rum. But it can support Rum-Ser). A support order is only valid if the supported unit does the specified action (e.g. Support Hold is only possible if the unit does not move. It fails even if the unit tried to move, but that move failed).
If an army is attacking a territory with support from another army (army owners are irrelevant for order resolution), we say that the attack has strength 2. If there are two moves to a territory, the one with a higher strength succeeds. If an army attacks a territory with strength 3, and the territory occupied by another army that is supported by only one other (strength 2), the defending army is dislodged and must retreat. If the attacks are of the same strength, the same rules apply as shown in the above examples.
Note: If there are two attacks of strength 2 on a territory occupied by an unsupported army, the two attacks bounce, and the occupying army remains there.
Instead of supporting hold of an army, you can counter a support by attacking the supporting army. If an army is attacked (even with strength of just 1), it must defend itself and cannot support another battle. Thus an army in Albania can help an attack on Bulgaria by hitting Serbia or Greece to “cut” that support, even though it cannot support directly. This is known as tapping.
4) Convoy—A fleet can convoy an army across sea territories.
This order is traditionally written as “F ENG C Lon-Bre” (Fleet in the English Channel convoys from London to Brest). When paired with “A Lon-Bre”, it lets armies move across water. Armies can move across multiple water territories if there is a fleet in each one, and each fleet has the same order. The fleet owner is not relevant, only the order is.
A convoy can be disrupted in any fleet in the chain is dislodged (forced to retreat—convoys can’t be “cut”).
After the moves, comes the retreat phase. Any units that have been dislodged can retreat to any unoccupied territories adjacent to the territory they were dislodged from. If no such territories exist (or if the player so chooses instead) the units are disbanded.
Finally comes the builds phase. Any supply centers that have units occupying them change ownership to the player who’s units those are. Unoccupied SCs keep their ownership from the last turn. So, to conquer a SC, you must hold it at the end of the Fall phase. The spring phase doesn’t matter in this regard.
A player can have as many units as they own SCs. If they lost SCs this year, they choose which units to disband. If they gained SCs, they can build new units in one of their unoccupied home SCs. Fleets can, of course, only be built in coastal SCs.
Note: It is possible to have many SCs, but not have anywhere free to build if, for example, you had to defend your home centers, so they are still occupied. Or if you lost them.
Some special cases:
Bulgaria, Span and Saint Petersburg have distinct coasts (south and north). A fleet occupying one of those can only move to territories neighboring that coast. Thus, for example, a fleet in Spain’s north coast can only move to MAO, Portugal or Gascony, but not to Western Mediterranean or Marseilles. If a fleet can move to either coast, it can give support in the entire territory. Only one coast can be occupied at the same time.
Constantinopole and Kiel have channels running through them, so they don’t have coasts.
If two dislodged units retreat into a same area, both are disbanded.
Two units cannot exchange territories in one turn (A->B, B->A will bounce), but three can rotate (A->B, B->C, C->A). Fleets cannot exchange territories using coasts (it’s the same territory).
You can retreat into an enemy SC and take control of it that way. Always know where the opponent can retreat when attacking them.
Like Chess, Diplomacy has some standard openings, for each country. You can read about most of them here. It might be worth to check out the ones related to your country.
Rules
This comment will explain the basic rules of the game. Reply to it with any questions relating to the rules themselves.
You can also read the rules on WikiBooks
The board initially looks like this.
You are randomly assigned a great European power. This is the only random element of the game. As you can see, the powers are not equal.
The map is divided into land and sea territories. These are traditionally abbreviated with 3 letters. The seas are uppercase (e.g. ION—Ionian Sea), while lands are written in lowercase (e.g. Bel—Belgium). Switzerland is unpassable. Some of the land territories contain Supply Centers, which are marked with a circle. There 36 of these. As soon as someone owns 18 (50%+1), they win the game. The SCs that are colored on the above map are a power’s Home Supply Centers. These have a special meaning for the power they originally belong to (for others, they are the same as neutral SCs).
There are two types of units: armies and fleets. The fleets can only occupy sea and coastal territories. Armies can only occupy land territories. A power can posses as many units as they own supply centers. All units are of equal strength.
A game year is consists of five phases, some of which may be skipped if there is nothing to be done:
1) Spring moves (AKA Diplomacy phase)
2) Spring retreats
3) Fall moves (AKA Diplomacy phase)
4) Fall retreats
5) Builds/Disbands
During a Moves/Diplomacy phase the players submit orders for every unit they own. Once all orders are submitted, they are evaluated simultaneously. There are 4 types of orders:
1) Hold—The unit does nothing, just holds its position.
This order is traditionally written as “A Ven Holds” (army in Venice holds) or “F BLA H” (fleet in Black Sea holds).
2) Move—The unit attempts to move to an adjacent territory.
This order is traditionally written as “A Ber-Mun” (army Berlin moves to Munich) or “F Lon-ENG” (fleet in London moves to the English Channel).
In a basic case where no other units attempt to move to a territory, the move succeeds, and in the next phase that unit is in the new territory. If a unit attempts to move to a territory occupied by another unit (friendly or not), that move will fail, unless the other unit moved out. If two units attempt to move to the same territory, neither move succeeds. This is known as a bounce. As an example, let’s assume there are units in Greece (Gre), Serbia (Ser) and Romania (Rum), while Bulgaria (Bul) is vacant.
A) A Ser-Bul, A Rum-Bul, A Gre-Bul; No moves succeed, everything remains as is entering the next phase.
B) A Ser Holds, A Gre-Ser, A Rum-Bul; Greece army doesn’t enter Serbia, Romanian army moves to Bulgaria.
C) A Ser-Bul, A Rum-Bul, A Gre-Ser; Serbia and Romania bounce in Bulgaria, meaning Serbia is not vacant. That means the Gre-Ser move fails as well, no one moves in the end.
D) A Ser-Gre, A Gre-Ser, A Rum-Ser; Serbia and Greece attack each other, nothing happens. Serbia is still occupied so Romania can’t move into it.
Note: It is possible for two armies (e.g. in Gre and Rum) to defend three territories (e.g. Gre,Bul,Rum) by bouncing themselves.
Note: When it comes to coastal territories (i.e. a land bordering a sea) that can be occupied by both armies and fleets, same rules apply to both.
Now the question is how to defeat an enemy unit. The third order type is:
3) Support—The unit helps another unit move/hold.
This order is traditionally written as “A Ser S Gre-Bul” (Army in Serbia supports the move to Bulgaria from Greece) or “A Rum S Bul Hold” (Army in Romania supports the Bulgarian unit’s hold).
A unit can offer support in any territory it could move to (e.g. Greece can’t support Ser-Rum, because it cannot move to Rum. But it can support Rum-Ser). A support order is only valid if the supported unit does the specified action (e.g. Support Hold is only possible if the unit does not move. It fails even if the unit tried to move, but that move failed).
If an army is attacking a territory with support from another army (army owners are irrelevant for order resolution), we say that the attack has strength 2. If there are two moves to a territory, the one with a higher strength succeeds. If an army attacks a territory with strength 3, and the territory occupied by another army that is supported by only one other (strength 2), the defending army is dislodged and must retreat. If the attacks are of the same strength, the same rules apply as shown in the above examples.
Note: If there are two attacks of strength 2 on a territory occupied by an unsupported army, the two attacks bounce, and the occupying army remains there.
Instead of supporting hold of an army, you can counter a support by attacking the supporting army. If an army is attacked (even with strength of just 1), it must defend itself and cannot support another battle. Thus an army in Albania can help an attack on Bulgaria by hitting Serbia or Greece to “cut” that support, even though it cannot support directly. This is known as tapping.
4) Convoy—A fleet can convoy an army across sea territories.
This order is traditionally written as “F ENG C Lon-Bre” (Fleet in the English Channel convoys from London to Brest). When paired with “A Lon-Bre”, it lets armies move across water. Armies can move across multiple water territories if there is a fleet in each one, and each fleet has the same order. The fleet owner is not relevant, only the order is.
A convoy can be disrupted in any fleet in the chain is dislodged (forced to retreat—convoys can’t be “cut”).
After the moves, comes the retreat phase. Any units that have been dislodged can retreat to any unoccupied territories adjacent to the territory they were dislodged from. If no such territories exist (or if the player so chooses instead) the units are disbanded.
Finally comes the builds phase. Any supply centers that have units occupying them change ownership to the player who’s units those are. Unoccupied SCs keep their ownership from the last turn. So, to conquer a SC, you must hold it at the end of the Fall phase. The spring phase doesn’t matter in this regard.
A player can have as many units as they own SCs. If they lost SCs this year, they choose which units to disband. If they gained SCs, they can build new units in one of their unoccupied home SCs. Fleets can, of course, only be built in coastal SCs.
Note: It is possible to have many SCs, but not have anywhere free to build if, for example, you had to defend your home centers, so they are still occupied. Or if you lost them.
Some special cases:
Bulgaria, Span and Saint Petersburg have distinct coasts (south and north). A fleet occupying one of those can only move to territories neighboring that coast. Thus, for example, a fleet in Spain’s north coast can only move to MAO, Portugal or Gascony, but not to Western Mediterranean or Marseilles. If a fleet can move to either coast, it can give support in the entire territory. Only one coast can be occupied at the same time.
Constantinopole and Kiel have channels running through them, so they don’t have coasts.
If two dislodged units retreat into a same area, both are disbanded.
Two units cannot exchange territories in one turn (A->B, B->A will bounce), but three can rotate (A->B, B->C, C->A). Fleets cannot exchange territories using coasts (it’s the same territory).
You can retreat into an enemy SC and take control of it that way. Always know where the opponent can retreat when attacking them.
Like Chess, Diplomacy has some standard openings, for each country. You can read about most of them here. It might be worth to check out the ones related to your country.