Fortifications of Portsmouth

The fortifications of Portsmouth are extensive due to its strategic position on the English Channel and role as home to the Royal Navy. For this reason, Portsmouth was, by the 19th century, one of the most fortified cities in the world. The fortifications have evolved over the centuries in response to changes in tactics and technology and the area defended has increased. While the first defences focused on Portsmouth harbour, in step with the fortifications of Gosport, later defensive structures protected the whole of Portsea Island and an increasing distance inland. At the same time, the fortifications of Portsmouth and Gosport became part of the wider fortifications of the Solent. Old Portsmouth, on the southwest corner of Portsea Island, has been walled for much of its history.

The first fortification in the area was Portchester Castle, which, ultimately, dates back to the Roman Portus Adurni. Its position allowed it to provide a degree of defence for the upper reaches of Portsmouth Harbour. The first recorded fortifications on Portsea Island appear to have been a wall constructed in 1212 around a primitive shipyard sited just to the north of what later became Camber Dock. The wall lasted less than twelve years.

During the 14th century, Portsmouth was subject to attacks in 1338, 1369, 1377 and 1380. Evidence suggests that simple earthworks were constructed and reconstructed around the settlement in response. The first structure built to defend Portsmouth proper was a wooden version of the Round Tower constructed between 1418 and 1426. Four years later, a second wooden tower was added on the opposite side of the harbour.

During Henry VII's rule, the Round Tower was rebuilt in stone and the Square Tower added. There is, however, some question as regards the extent to which it was meant to be a defensive structure. It appears likely that what is now known as the "saluting platform" was also built during Henry VII's reign.Southsea Castle at the southern tip of Portsea Island was built by his son and successor Henry VIII.

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