A respectable fleet, commanded by Commodore Saltonstal, and an army of near four thousand men, under General Lovell, were prepared with so much celerity, that the whole armament appeared in the Penobscot as early as the 25th of July.
M'Clean had taken possession of a peninsula on the eastern side of Penobscot, and had intrenched the isthmus connecting it with the continent.

The part towards the river was steep and difficult of access; and was also defended by his frigates and batteries, the principal of which was constructed about the centre of the peninsula.
After being repulsed in his first attempt, General Lovell effected a landing on the western part of the peninsula, where he ascended a precipice of two hundred feet; and, with the loss of only fifty men killed and wounded, drove the party which defended it from the ground.
A battery was erected within seven hundred and fifty yards of the main work of the besieged, and a warm cannonade was kept up for several days on both sides.
Perceiving the difficulty of carrying the place with a militia impatient to return to their homes, General Lovell represented his situation to the government of Massachusetts, who applied to General Gates, then commanding at Providence, for a reinforcement of four hundred continental troops.

This request was readily granted, and Jackson's regiment was ordered to Penobscot.

In the mean time an ineffectual cannonade was continued, and preparations were made to storm the works on the arrival of the expected reinforcements.
Such was the posture of affairs on the 13th of August, when Lovell received information that Sir George Collier had entered the river with a superior naval force.

He re-embarked his whole army the following night, and drew up his flotilla in a crescent across the river, as if determined to maintain its position.