ARCHIDAMIAN WAR, the war between Athens and Sparta, with their respective allies, which began in 431 B.C. with the surprise attack of Thebes on Plataea. The name is taken from Archidamus, king of Sparta, who on the outbreak of the war led the first invasion of Attica. Over the victims of this raid Pericles delivered his famous funeral speech (Thuc. ii. 34, seq.) . The war was marked by the great plague and the campaign of Brasidas in the north. It was ended by the peace of Nicias (421). It is gen erally, and with reason, considered as merely the earlier part of the Peloponnesian War. (See GREECE : History.)