Longships were vessels made and used for trade, exploring, and raiding. They are usually thought of as Viking ships but were used by early people on the Baltic Sea and the North Sea. It was the Vikings who mastered the design of light fast longships that could also go up rivers. At the beginning of the Anglo-Saxon period in Britain, the invading groups of Angles, Saxons, Frisians and Jutes arrived in longships. From that time on longships were also being built and used in the British Isles. When the Normans conquered England in 1066, William the Conqueror used a large fleet of longships to transport his army to England. 