Fortifications of Plymouth

The fortifications of Plymouth in Devon are extensive due to its natural harbour, its commanding position on the Western Approaches and its role as the United Kingdom's second largest naval base after Portsmouth. The first medieval defences were built to defend Sutton Harbour on the eastern side of Plymouth Sound at the mouth of the River Plym, but by the 18th century, naval activity had begun to shift westward to Devonport at the mouth of the River Tamar. During the Victorian era, advances in military technology led to a huge programme of fortification encompassing the whole of Plymouth Sound together with the overland approaches. Many of these works remained in military use well into the 20th century.

At the time of the Norman Conquest, Plymouth was a tiny settlement at Sutton Harbour, but in 1295 and 1357, royal expeditions to France had used Plymouth as a final gathering place before making the crossing. In in 1377, a murage grant was received to fund its fortification, although what form these works took is unknown.

Following a French raid on Plymouth in August 1403, King Henry IV ordered the prior of Plympton and the abbot of to further fortify the town with walls and towers. The eventual result of this was a castle with four towers overlooking the town and harbour, which seems to have been largely funded by the townspeople and was under the control of Plymouth's mayor and aldermen. Only a small section of the castle fabric survives, located in Lambhay Street, at the head of a flight of stairs leading down to the Mayflower Steps on the quayside.

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