Diplomacy is a strategic board game created by Allan B. Calhamer in 1954 and released commercially in the United States in 1959.

[5] The rough form of Diplomacy was created in 1954, and its details were developed through playtesting until the 1958 map and rules revisions.

Balancing units to supply center counts is done after each game-year, which involves two seasons of play: Spring and Fall.

Further acquisition of supply centers becomes a zero sum dynamic with any gains in a player's resources coming at the expense of a rival.

Although the game starts in 1901, the map generally reflects the political boundaries of Europe in 1914, just before the outbreak of the Great War.

Additionally, North Africa and Tunis start the game as neutral, despite these regions being part of the French colonial empire in 1914.

In the negotiation phase, players discuss tactics and strategy, form alliances, and share intelligence or spread disinformation.

Communication and trust are highly important; players must forge alliances with others and observe their actions to evaluate their trustworthiness.

For 4 or 5 players, it is suggested that the 'Wilson' or 'Public Press' rule applies which means that all discussions must take place in the open at the table with no whispers or secret signals.

The game introduces many rules changes such as money, bribery, three seasons per year, garrisons, and random events such as plague and famine.

[14][15] Ard-Rí is a map by Stuart John Bernard based on pre-Christian Ireland (though it anachronistically includes Vikings), created in 1998, and published by Stupendous Games in 2000.

Classical is a map by Andy D. Schwarz and Vincent Mous based on the ancient world after the death of Alexander the Great, created in 1998, and published by Stupendous Games in 2000.

[17][15] Based on the Three Kingdoms in Ancient China, it was created by Edi Birsan to introduce the basic ideas of the main game to a Chinese audience with a setting more close to their own historical experience.

One of the most notable non-commercially published is the Youngstown variant which is an extension of the normal map, including Asia and colonies there.

Some conventions are centered on the games and have a highly competitive atmosphere; others have more focus on meeting and socializing with other players from the postal or e-mail parts of the hobby.

[24] Many of the larger multi-game conventions, such as the World Boardgaming Championships, Gen Con, Origins, ManorCon, TempleCon, and Dragonflight also host Diplomacy tournaments.

The current largest example of a dedicated online Diplomacy server with automatic adjudicators is Backstabbr.com, developed by Tile Games.

[30] According to reviewer Martin Croft, in the early 1980s, Two players managed to get into trouble with the police ... [while] involved in complex negotiations about an attack on the gamer playing Britain.

[30]In the 1990s and 2000s, the number of postal Diplomacy zines has reduced as new players instead joined the part of the hobby that plays over the internet via e-mail or on websites.

In order to reduce postage and printing costs, as well as for environmental reasons, several zines (e.g. Western Front, Maniacs Paradise) are distributed to subscribers via emailed links to the zine's web page when a new issue appears, or are emailed out as PDF files, for subscribers to read on screen or print out as they choose.

[28] The GEnie online service offered fully automated versions of Diplomacy and variants to subscribers.

"[36] Paradox Interactive released a new computer version in 2005, which was given negative reviews, partly due to the odd grunts the game used to express the reactions of the AI players during the Movement phase.

[37][38][39] None of the computer games supported either text or voice chat, which limited the possibilities for complicated alliances.

[39] In 2011, artificial intelligence scholars noted that work on Diplomacy-focused AI has been carried out since mid-1980s, but so far this endeavour met "little success".

In November 2022, Meta Platforms announced that they had developed an AI to play Diplomacy online at a competitive level, ranking in the top 10% of players.

[42][43] In his 1977 book The Comprehensive Guide to Board Wargaming, Nick Palmer thought that despite "primitive" movement and combat rules, "the game has an extraordinary charm all its own, based on the fascinating interplay of alliances between the seven players".

The double-dealing required attracts some people irresistibly and repels others just as strongly, but the interaction in Diplomacy is the model for all other 'power politics' games."

[49] Michael Portillo, British journalist, broadcaster, and former Member of Parliament and cabinet minister, is known to have played the game while studying at Harrow County School for Boys.

Game designer Larry Harris explained: "I am convinced that Allan Calhamer's masterpiece should be part of every high school curriculum.

Don't tell the kids, but it teaches history, geography, the art of political negotiation, and something else – some healthy critical skepticism.