Soon after the affair at Monk's corner, Sir Henry Clinton received a reinforcement of three thousand men from New York. This addition to his strength enabled him to detach largely to the aid of Lieutenant Colonel Webster, after which Lord Cornwallis took command of the troops on that side of Cooper River. [Sidenote: April 20.] Upon this change of situation, Lincoln called another council of war. Notwithstanding the multiplied difficulties attending an evacuation of Charleston, he appears to have been still inclined to it. But a number of fortunate circumstances must have concurred to render a retreat possible; and the attempt was effectually prevented by the opposition of the civil government. The opinion seems to have prevailed, that the escape of the garrison would be followed by the destruction of the town, and the ruin of its inhabitants. The council advised that a capitulation should be proposed, and that the town should be surrendered on condition that the garrison should be at liberty still to bear arms, and that the inhabitants should be secured in their persons and property. These propositions being rejected, hostilities recommenced. The besiegers had completed their second parallel, and had begun the third, when Colonel Henderson made a vigorous sally on their right, which was attended with some success. That this was the only sortie made during the siege, is to be ascribed to the weakness of the garrison. General Lincoln deemed it necessary to reserve all his strength to man his lines in the event of an assault, or to force a retreat, should he determine to evacuate the city. In this state of things, General Du Portail, who had been directed to join the southern army, was conducted by secret ways into the town. He perceived the impossibility of defending the place, and repeated the proposition for attempting a retreat. This proposition was again rejected; and it only remained to defer the surrender as long as possible, in the vain hope that some fortunate occurrence might bring relief. [Sidenote: The garrison of fort Moultrie surrender themselves prisoners of war.] Every day diminished this hope, and added to the difficulties of the besieged. The admiral took possession of Mount Pleasant, which induced the immediate evacuation of Lamprere's point; soon after which the garrison of fort Moultrie, amounting to about two hundred men,[22] surrendered themselves prisoners of war. On the same day, the cavalry which had escaped the disaster at Monk's corner, and had been reassembled under the command of Colonel White, of New Jersey, was again surprised and defeated by Lieutenant Colonel Tarlton at Lanneau's ferry. [Footnote 22: After the fleet passed the fort, Colonel Pinckney and a part of the garrison were withdrawn.]