Constructed in 1759, the five substantial storehouses as a group were known as a magazine. It is No 5 storehouses that survives; the other four were demolished in the early 1970s as were most of the other military buildings. All that was given a new lease of life was the Proofing house where the poweder was first proofed (tested), the Clock Tower, some of the security walls and of course No 5, know known as magazine No 5 as it is the only storehouse left standing. Once proofed and tested it could be graded for use in pistols, heavy mortars or cannon it would then be stored until required by the army or navy. During the Napoleonic wars Purfleet was exceptionally busy.

Each storehouse could hold 10,400 barrels of powder that was increased in times of war to by 400 barrels. Each barrel weighed (45kg) 100lb. The five storehouses could store up to 54,000 barrels that is 24.5 metric tonnes.

The magazine was protected by inner and outer security walls with a Garrison of soldiers to guard the site. The work within the magazine was undertaken by civilians. The site remained in use by the military throughout the 19th and into the 20th century up to 1962, when the land with its buildings was purchased from the Ministry of Defence by Thurrock Council. As it has already been astated most of the buildings were demolished to make way for housing. On completion of the estate it was named ‘The Garrison’ and all the roads were named after Armoured Fighting Vehicles.