[1] The overlarge naval and military establishment at Bermuda in the Nineteenth Century and the first half of the Twentieth Century was due to the colony's role as an Imperial fortress, the lynchpin of Britain's supremacy in the western Atlantic Ocean and (after the completion of the Panama Canal and the establishment of alliance, amity, and common interests with the United States of America from the First World War, onwards) the Eastern Pacific Ocean, and upon the coast of America (as had been demonstrated during the American War of 1812, when the blockade of the Atlantic seaboard of the United States by the squadron of the then-North America Station of the Royal Navy had been orchestrated from Bermuda, with military forces from Bermuda working with the squadron in a succession of amphibious operations, including the Battle of Craney Island, culminating in the 1814 Chesapeake campaign that included Battle of Bladensburg, capturing and burning Washington, DC, and raiding Alexandria, Virginia),[2][3][4][5][6] As Britain could afford neither to lose the use of Bermuda as a base for British forces, nor to allow it to fall into the hands of an enemy that would make similar use of it against Britain, vast sums were invested during the Nineteenth Century on its defence, which had previously been left from 1612 to 1701 to the non-professional military forces (militia and volunteers),[7] with the addition of a small force of regular infantry from 1701 'til the Napoleonic Wars (excepting several years between the Seven Years' War and the American War of Independence during which there were no regular soldiers).

The regular Royal Artillery anticipated the same employment, which could be met more economically in both material and manpower terms by a handful of field guns kept at Prospect Camp and drawn wherever required by horse team.

The Battle of Wreck Hill had taken place here during the American War of Independence, when entry via the Hogfish Cut was attempted by two rebel sloops under the command of a pair of Bermudian brothers who had settled in South Carolina, but were familiar with Bermuda's reefs and channels.

The rebel sloops landed men to act as infantry who attacked the fort from behind, forcing the gunners to abandon it, then spiked its guns before retreating themselves.

As the advent of the torpedo boat meant a fast attacking force of small vessels capable of wreaking havoc on the naval squadron anchored at Grassy Bay could enter the Great Sound by this way, fixed batteries were maintained in the West End forts, though generally with smaller guns than at the East End suitable for use against small, unarmoured, but fast-moving, vessels at close range.

This line would be defended with small arms by infantry behind the ramparts, but artillery support was provided by two 64 Pounder Rifled Muzzle-Loader (RML) gun on Moncrieff disappearing mounts.

The guns had a range of 4,000 yards, capable of firing not only on infantry advancing from the Main Island, but also on vessels navigating the western channel or the Great Sound.

The keep containing the eastern gun emplacement is polygonal, of the Prussian style, with a defensive wall and dry moat to the rear defended by a block house.

As part of the extensive cutbacks made to the British Army in the period of Government austerity that followed the First World War, the Bermuda Garrison was run down in stages.

[13] Although the District Establishment of the Royal Artillery maintained guns in a handful of other batteries, and the General Officer Commanding-in-Chief Bermuda (who was also the civil Governor)[14] at the start of the Second World War requested the addition of more 9.2 guns to the defences (together with re-activating the three already in place at St. David's Battery and Fort Victoria), the British Government could not spare funds on improving the colony's defences, or on building an airfield sorely need for tans-Atlantic flight (there being two air stations at Bermuda at the start of the war, RAF Darrell's Island and Royal Naval Air Station Bermuda on Boaz Island, but both only for use by flying boats).

The United States Army also built a network of Base End Observation Posts (roughly a dozen identical towers on hilltops about Bermuda) to co-ordinate the fire of all of the British as well as American guns.