Deal Castle is one of a network of coastal artillery forts built along the south coast of England by Henry VIII to deter French and Spanish invasion. Also known as Henrician castles or device forts, they all share a circular plan that enabled guns to cover every angle. 

The fort was besieged and badly damaged during the English Civil War. It was also hit by German bombing during WW2, when in use as an observation post for an artillery battery placed further along the coast.