Whilst the army was thus actively employed, the fleet did hot remain idle. A squadron of frigates, with two bomb-ships, under the command of Captain Gordon, of the Sea horse, penetrated up the Potomac, and appeared before Alexandria. The whole of the militia of the district was at this time called away for the defence of the capital, consequently no place could be less prepared to resist an invader than that city. A party accordingly landed from the ships without opposition, and having destroyed the barracks, public works, and all the cannon which they found on shore, they seized a number of schooners and other small craft then lying in the harbour, and loading them with flour and tobacco to a considerable amount, prepared to rejoin the fleet in the bay.

But by this time the country was alarmed; a detachment was sent from the main army, and being joined by the reserve of militia, it was determined to intercept the squadron on its return. With this view, several pieces of heavy cannon were mounted upon a steep part of the bank, where the river, in making an angle, narrows considerably in its channel. Thither also hastened large bodies of infantry; and before the frigates had begun to weigh anchor nearly 5000 men were assembled to prevent their passage.