A galley is a long single or half-decked vessel of war, with low free-board, propelled primarily by oars or sweeps, but also having masts for sails. The word is used generally of the ancient war vessels of Greece and Rome of various types (e.g. the trireme), whose chief propelling power was the oar or sweep, but its more specific application is to the medieval war vessel which survived in the navies of the Mediterranean sea-powers after the general adoption of the larger many-decked ship of war, propelled solely by sail-power. The Battle of Lepanto (1571) was the last great naval battle in which the galley played the principal part.
The "galleass" or "galliass" was a larger and heavier form of galley; it usually carried three masts and had at bow and stern a castellated structure. The "galliot" was a small, light type of galley. The galleon was a sailing ship of war and trade, shorter than the galley and standing high out of the water with several decks, chiefly used by the Spaniards during the 16th century in the carrying of treasure from the Americas. The number of oars or sweeps varied, the larger galley having twenty-five on each side; the galleass as many as thirty-two, each being worked by several men.
The labor of rowing was from the earliest times often performed by slaves or prisoners of war. It became the custom among the Mediterranean powers to sentence condemned criminals to row in the war galleys of the state. Traces of this in France can be found as early as 1532, but the first legislative enactment is in the Ordonnance d'Orléans of 1561. In 1564 Charles IX of France forbade the sentencing of prisoners to the galleys for less than ten years. The galley-slaves were branded with the letters GAL. At the end of the reign of Louis XIV of France the use of the galley for war purposes had practically ceased, but the corps of the galleys was not incorporated with the navy till 1748. The headquarters of the galleys and of the convict rowers (galériens) was at Marseilles. The majority of these latter were brought to Toulon, the others were sent to Rochefort and Brest, where they were used for working in the arsenal. At Toulon the convicts remained (in chains) on the galleys, which were moored as hulks in the harbour. Shore prisons were, however, provided for them, known as bagnes, "baths," a name given to such penal establishments first by the Italians (bagno) , and said to have been derived from the prison at Constantinople situated close by or attached to the great baths there. The name galerien was still given to all convicts, though the galleys had been abandoned, and it was not till the French Revolution that the hated name with all it signified was changed to forcat. In Spain galera is (in 1911) still used for a criminal condemned to penal servitude.
A vivid account of the life of galley-slaves in France is given in Jean Marteilhes's Memoirs of a Protestant, translated by Oliver Goldsmith, which describes the experiences of one of the Huguenots who suffered after the revocation of the Edict of Nantes.