A duumvirate is an alliance between two equally powerful political or military leaders.[1] The term can also be used to describe a state with two different military leaders who both declare themselves to be the sole leader of the state.
The tiny European nation of Andorra is nominally a duumvirate, as it is ruled by two co-princes, one of whom is Nicolas Sarkozy, the President of France, the other of whom is Joan Enric Vives i Sicília, Bishop of the Diocese of Urgell, although the Andorran prime minister wields de facto power as the head of government. Duumvirates in history include the city-states of Carthage, ruled by two mayors (Suffets), and Ancient Rome, ruled by two Consuls. Sparta was also ruled by two kings, thus a duumvirate.
Some political parties have duumvirates, sometimes, such as is the case of Lindsey German and John Rees in the Socialist Workers Party in Britain.
The First Whitlam Ministry in Australia is sometimes called the "Duumvirate" because it consisted entirely of the Prime Minister, Gough Whitlam, and his deputy, Lance Barnard, who between them split up all ministerial and quasi-ministerial positions for two weeks in December 1972.
It has been suggested[2] that Vladimir Putin and Dmitri Medvedev represent a modern Russian duumvirate, sometimes referred as тандемократия, “tandemocracy”, a compound of “tandem” and “-cracy”, at the same time a portmanteau with “democracy” (see Sovereign democracy).