 St Catherine 's Castle was built as a consequence of the international tensions between England , France and the Holy Roman Empire in the final years of the reign of King Henry VIII . Traditionally the Crown had left coastal defences to the local lords and communities , only taking a modest role in building and maintaining fortifications , and while France and the Empire remained in conflict with one another , maritime raids were common but an actual invasion of England seemed unlikely . Modest defences , based around simple blockhouses and towers , existed in the south @-@ west and along the Sussex coast , with a few more impressive works in the north of England , but in general the fortifications were very limited in scale . 
