From the time the Romans first landed on British shores our island has lived with the constant threat of invasion, although the last successful invader was William the Conqueror in 1066 (some would argue William of Orange but he was 'invited'). Since that time, varying types of fortification have been created around the coasts to repel further invasions from the Spanish, French, Dutch and, most recently, the Germans. Most of the earlier fortifications have been classified as castles, but this section deals specifically with those constructed from the late 17th century onwards.