During the Second World War, the similar shape, size and location of Hayling to neighbouring Portsea Island was used as a decoy to draw fire from important military targets. With fires being lit around Hayling to simulate bomb damage, Germans bomber crews were frequently fooled by the ruse resulting in Hayling suffering heavy bomb damage. Hayling’s main defence against this raid was in the form of two anti-aircraft batteries, one at North Hayling Halt and one here at Sinah Common.

Much of the original defences are still visible at Sinah Common and have been preserved as a memorial to six gunners who died during a particularly heavy raid in April 1941. Two of the huge emplacements, which would have previously housed the antiaircraft guns, have been converted to a recreation area, whilst the heavily reinforced structures of two other site buildings are still visible.

Through the fence at the back of Sinah Common you will also see the lake known locally by many as Sinah Lake (although Sinah Lake is in fact a channel running north of the Ferry). Despite being so close to the sea front, this is in fact a fresh water lake sourced by the fresh water springs that surface at Havant.