The Device Forts
are a series of artillery fortifications
built in England
by Henry VIII
. After his divorce of Catherine of Aragon
left England politically isolated, a treaty between France
in 1538 aroused fears of invasion. Although the threat was short-lived, it stimulated the largest defence programme since Saxon
times. Henry took a personal interest in the military engineering
techniques of the time, and approved and amended the designs himself.
Some 30 works were started in 1539, but the key ones are forts at:
All of these survive except Sandown, Kent, lost to coastal erosion.
They are generally in the form of a central round tower surrounded by a variety of concentric elements. Short and squat, with normally 3 tiers of long-distance offensive armament and a couple of tiers of defensive armament. The bays had wide splays for easy traverse
of the guns
, walls were thick and curved to deflect shot, and the medieval portcullises
Later ones in the chain, however, took into account more recent developments and were of a more angular form, with triangular bastions, as at Yarmouth.