The garrison consisted of the battalions of Artois, Bourgogne, Cambis, and Volontaires Etrangers, with two companies of artillery, and twenty-four of colonial troops; in all, three thousand and eighty men, besides officers.

In the harbour lay five ships of the line and seven frigates, carrying five hundred and forty-four guns, and about three thousand men, and there were two hundred and nineteen cannons and seventeen mortars mounted on the ramparts and outworks, and forty-four in reserve.
Of the outworks, the strongest were the grand battery at Lighthouse Point, at the mouth of the harbour; and that on Goat Island, a rocky islet at its entrance.

The strongest front of the works was on the land side, across the base of the triangular peninsula on which the town stood.

This front, twelve hundred yards in extent, reached from the sea, on the left, to the harbour on the right, and consisted of four strong bastions with connecting works.
The best defence of Louisbourg, however, was the craggy shore, which, for leagues on either side, was accessible only at a few points, and, even there, a landing could only be effected with the greatest difficulty.

All these points were watched, for an English squadron, of nine ships of war, had been cruising off the place, endeavouring to prevent supplies from arriving; but they had been so often blown off, by gales, that the French ships had been able to enter, and, on the 2nd of June, when the English expedition came in sight, more than a year's supply of provisions was stored up in the town..