An anti-submarine net running between York Redoubt and McNab's Island in 1942
York Redoubt was a key element in the defence of Halifax Harbour in the 19th and 20th centuries, and underwent many additions to its fortifications. It was a command centre for harbour defences in World War II, which included observation posts, a defensive Minefield and a new gun battery below the fort at Sleepy Cove covering the anti-submarine net which stretched across the harbour's entrance from Fort McNab on McNabs Island.
York Redoubt remained in military use until 1956. Buildings in the redoubt complex include what remains of the Duke of York's Martello tower (1798) and fortifications circa 1800, with additional expansions circa 1900 and advanced fortifications and artillery from the Second World War. York Redoubt has many examples of the rifled muzzle loader cannon from the 1870s period. An open-air collection of unmounted cannon within the fort has several pieces of artillery of various periods, including a large 10-inch breech loader that had been mounted at the Sandwich Point battery, part of the York Redoubt complex.
Structures at the waters edge at Sleepy Cove battery (now closed to the public) include three search light batteries, two cement lookout towers and two gun emplacements which originally held two 12 pounder guns, but were later replaced with 6 pounder guns.
On 28 June 1985, Canada Post issued 'York Redoubt, N.S.' one of the 20 stamps in the “Forts Across Canada Series” (1983 & 1985).
The series of four gun emplacements was constructed during World War I one kilometre away from the main fort at York Redoubt to protect the approaches to Halifax Harbour. During the Second World War the two dated 9.2 inch breach loading guns were removed, but the two 6 inch breach loaders were retained throughout the war. The battery is currently derelict and completely contained within Department of National Defence fenced land and is strictly off limits to the public.