On the night of March 31st, 1916, gunners at Purfleet, protecting the Royal Gunpowder Magazines, engaged anti-aircraft fire against Zeppelin LZ15, damaging the airship so badly she finally crashed in the sea at the Nore. Seventeen survivors were rescued and imprisoned.

Captain J. Harris of the Purfleey garrison put in a claim for the Lord Mayor's prize, but the War Office ruled that gunners could not get a money prize for doing their job. Instead, the prize was converted into gold medallions, which were given to each of the Purfleet gunners who engaged the enemy that night. The medal is inscribed "Well Hit, LZ15 31st March 1916".

A Thurrock heritage plaque marks this event. It is fixed to the wall of the Woodlands pre-school in West Thurrock. This stands close to the site of the large wall that used to surround the magazine site near which the anti-aircraft guns were mounted.