The Hydra class of ironclads composed three ships, Hydra, Spetsai, and Psara. The ships were ordered from France in 1885 during the premiership of Charilaos Trikoupis, as part of a wider reorganization and modernization of the Greek armed forces, which had proved themselves inadequate during the Cretan uprising of 1866. Launched in 1889 and 1890, the ships were ready for service with the Greek Navy by 1892. They were armed with a main battery of three guns and five guns, and had a top speed of .