A large concrete reserve ammunition magazine for the major naval gun batteries in Sydney Harbour and Canso Strait was built at Johnstown. Opened in the fall of 1943, the complex consisted of 3 magazines, similar to the ones at
Debert, Nova Scotia and
McGivney, New Brunswick. Post-War, the site was used as a sub-depot of No, 31 Ordnance Depot in Debert, staffed by a single Private. The depot closed on 18 March 1957. All that remains is the laboratory building on the west side of Highway 4, south of Johnstown, now a private residence. ==References==