The island is perhaps best known today as the home of the Irish Naval Service headquarters, but long before the Irish state came into being, it was a site of considerable British military infrastructure, including a substantial barracks whose physical presence on this small island speaks to just how seriously the Crown took the defence of Cork Harbour and the approaches to Munster.

The island's military history stretches back to at least the late medieval period, but it was during the sixteenth, seventeenth, and eighteenth centuries that Haulbowline was developed in earnest as a fortified and garrisoned position. The British Admiralty took a particular interest in the island, eventually establishing a naval dockyard there that would become one of the most significant in Ireland. A barracks on such a site would have housed the soldiers and sailors responsible for protecting both the dockyard facilities and the wider harbour. Control of Cork Harbour mattered enormously, both commercially and strategically, and Haulbowline was central to that control. After Irish independence, the island transferred to the new state and the Naval Service has maintained a presence there ever since.