Last night at 12 o'clock, the enemy precipitately decamped and returned to their boats, leaving behind him, under medical attendance, eighty of his wounded including two officers, 14 pieces of his heavy artillery, and a quantity of shot, having destroyed much of his powder. Such was the situation of the ground he abandoned, and of that through which he retired, protected by canals, redoubts, entrenchments and swamps on his right, and the river on his left, that I could not, without encountering a risk which true policy did not seem to require, or to authorize, attempt to annoy him much on his retreat. We took only eight prisoners.

Whether it is the purpose of the enemy to abandon the expedition altogether, or renew his efforts at some other point, I do not pretend to determine with positiveness. In my own mind, however, there is but little doubt, that his last exertions have been made in this quarter, at any rate for the present season, and by the next I hope we shall be fully prepared for him. In this belief I am strengthened not only by the prodigious loss he has sustained at the position he has just quitted, but by the failure of his fleet to pass fort St. Philip.

His loss on this ground, since the debarkation of his troops, as stated by the last prisoners and deserters, and as confirmed by many additional circumstances, must have exceeded four thousand; and was greater in the action of the 8th than was estimated, from the most correct data then in his possession, by the inspector general, whose report has been forwarded to you. We succeeded, on the 8th, in getting from the enemy about 1000 stand of arms of various descriptions.

Since the action of the 8th, the enemy have been allowed very little respite-my artillery from both sides of the river being constantly employed, till the night, and indeed until the hour of their retreat, in annoying them. No doubt they thought it quite time to quit a position in which so little rest could be found.

I am advised by major Overton, who commands at fort St. Philip, in a letter of the 18th, that the enemy having bombarded his fort for 8 or 9 days from 13 inch mortars without effect, had, on the morning of that day, retired. I have little doubt that he would have been able to have sunk their vessels had they attempted to run by.

Giving the proper weight to all these considerations, I believe you will not think me too sanguine in the belief that Louisiana is now clear of its enemy. I hope, however, I need not assure you, that wherever I command, such a belief shall never occasion any relaxation in the measures for resistance. I am but too sensible that the moment when the enemy is opposing us, is not the most proper to provide for them.