A brig was a sailing vessel with two square-rigged masts, one fore, one main; although some large brigs had three masts, like the Nemesis. During the Age of Sail, brigs were seen as fast and maneuverable and were used as both naval warships and merchant vessels. Their use dated back to before the 1600s, but were especially popular in the 18th century. They are not to be confused with a brigantine, which were not square-rigged.