Kent artillery fort. 16th-century artwork of a design for an artillery fort on the Kent coast, England, almost certainly Deal Castle. The title reads: 'Castle in the Downes'. Deal Castle was one of a series of fortifications, known as Device Forts or Henrician Castles, built on the orders of King Henry VIII. Deal Castle was built between 1539 and 1540. The central citadel is surrounded by six semi-circular towers. A further six semi-circular bastions form the outer wall, overlooking a a dry moat with a wooden drawbridge. Hundreds of cannons were mounted on the fort's five different levels. This artwork dates from 1539.