Roman emperor (from 70 to 79) and tenth of the 12 Caesars, born in the Sabine territory of humble parentage; rose by his valour to high rank in the army and in favour with it, till at length he was elected by it to the throne; he had waged war successfully in Germany, Britain, and at Jerusalem, and during his reign, and nearly all through it, the temple of Janus was shut at Rome.