Originally constructed in 1798, on the site of the former North Castle Battery above Chain Rock, it was named for Vice Admiral William Waldegrave (1753-1825) who served as Naval Governor in Newfoundland from 1797 to 1800. The site commands a strategic location to provide protection to the entrance of the harbour. The battery was maintained until the late-1860s and was reactivated in July, 1916 when the Legion of Frontiersmen was assigned to man the battery, along with members of HMS Calypso. Repaired and expanded, it included two powder magazines, a mess hall, office, and living quarters. Over the centuries, it has been referred to as both a fort and a battery – called a fort primarily during periods of engagement, as it was during the First World War. Fort Waldegrave worked in concert with the government tug, Fiona, which had a search light focused on the narrows and Chain Rock battery. Beginning in October 1916, a boom was placed across the Narrows from sunset to sunrise each day. There was an incident when the famous sealing captain, Abram Kean, gave rise to the only close-call of the Fort Waldegrave gun being fired. Running ahead of a brewing storm, he crashed his vessel through the defence boom which began a chain of reaction, ending with the second in command at Fort Waldegrave having to physically restrain Lt. E.W. Vere Holloway, known to be a stickler for the rules, from firing upon the friendly vessel.
During WW1, a shield was carved in the rock face below the gun placement by the men assigned to Fort Waldegrave. It remains visible below the gun placement, along the footpath connection of the Harbourside Walk East of the Grand Concourse. Following the Armistice, Fort Waldegrave was closed in December, 1918. While the granite that forms the semi circle at the Fort Waldegrave gun battery is the original, much of the quarried stone from the dismantled buildings was used to repair the Anglican Cathedral in the 1940s and may still form basement foundations for some houses in The Battery.