York Redoubt was first fortified in 1793, when war broke out between Britain and France. General James Ogilvie, the British commander at Halifax during this time, built a two-gun battery along the south shore of the Northwest Arm, near the entrance, to help defend the harbour.
The defences were later improved by Prince Edward, the fourth son of King George III, when he was commander at Halifax from 1794 to 1800. By 1800 the site had an eight-gun battery and a round Martello Tower, with a signal mast to provide early warning of an enemy attack. Edward named the site York Redoubt in honour of the Duke of York, his brother.