The inter-war years saw considerable changes in the organisation of troops responsible for manning the Island whose establishment in 1932 consisted of one captain, one district officer, two master gunners, one sergeant, one bombardier, three tradesmen, four gunners and five civilian district gunners. This Fire Command unit covered the defence of the nearby mainland as well.
In 1939 there were two 6 inch and five 12 pounder guns on the Island but within a month or two of hostilities some of these were removed and others took their place. A 40 m.m. A.A. gun was installed, the present pier constructed, the slipway strengthened, an ammunition hoist (replaced by the present new one) built and a tall gunnery control erected on top of the island which was demolished by the army in the 1950's. There were also concrete bunkers built, gun sites strengthened and a minefield control post operational from the island which would have detonated mines placed over much of the Sound, had an invasion taken place. By April, 1941, there were 490 troops stationed on this key Island. The number remained around this figure for most of the war. In spite of the German raids on Plymouth and its dockyard the island only suffered slightly from thirty-one incendiaries and several high explosive bombs falling on and around it. One person was injured and the canteen roof was damaged. The 40 m.m. gun engaged an enemy aircraft on 13th June, 1944.
The end of the war heralded for Drake's Island its last years as a military fortress during which its use and value to the overall defence plans of the country diminished to such an extent that by the 1950's it was deemed unnecessary to man it any longer. The scale and change in warfare through harnessing the atom finally brought to an end hundreds of years of military occupation and gave opportunities for this small Island to be put to other uses. In 1956 the Minister of Defence announced that the Coast Artillery was to be disbanded at which time the Island had six l2 pounder guns still operational and manned by twelve officers, eleven W.O.'s and N.C.O.'s and 114 rank and file. In December, 1956, Ministry of Supply contractors removed all the armaments and fittings and demolished much of the gun positions and other military features built during the last war.