The garrison totalled around 400 men; two companies from Guise's, two from Johnsons and one from the Campbell of Argyll Militia. A well-built, modern position, its triangular shape was designed to use the head of Loch Linnhe as cover; it had six 12-pounder cannon, eight 6-pounders, seven smaller pieces, two 13-inch mortars and eight coehorns, with plenty of ammunition. Additional firepower was provided by the sloop of war "Baltimore" and the "Serpent", a bomb vessel; this made it a formidable target, its only weakness being lack of a permanent water supply.