The Frigate was a fast and powerful sailing warship that evolved to fill several important navy roles. It was used as the eyes of the main fleet of ships-of-the-line and it raided enemy shipping. The Frigate was powerful enough to overcome most of its prospective opponents and fast enough to escape those it could not outgun. Because of its speed and strength, the Frigate was often also employed in the role of convoying merchant vessels in time of war, many of which were carrying troops and equipment. The Frigate was the most useful and dominant naval vessel until the appearance of the Ironclad.