The works of St. Philip consisted of the fort proper, a structure of brick and earth mounting in barbette four VIII-inch columbiads and one 24-pounder; and two water batteries on either side of the main work, the upper mounting sixteen 24-pounders, the lower, one VIII-inch columbiad, one VII-inch rifle, six 42-pounders, nine 32s, and four 24s. There were here, then, forty-two guns commanding the river below the bend, up which the ships must come, as well as the course of the stream in their front. Besides these there were one VIII-inch and one X-inch mortar in the fort; one XIII-inch mortar, whose position does not appear; and a battery of four X-inch sea-coast mortars, situated below and to the northeast of the lower water battery. These last pieces for vertical shell-firing had no influence upon the ensuing contest; the XIII-inch mortar became disabled at the thirteenth fire by its own discharge, and the X-inch, though 142 shell were fired from them, are not so much as mentioned in the reports of the fleet. Fort Jackson, on the southern bank of the bend, was a pentagonal casemated work, built of brick. In the casemates were fourteen 24-pounder smooth-bore guns, and ten flanking howitzers of the same calibre. Above these, in barbette, were two X-inch and three VIII-inch columbiads, one VII-inch rifle, six 42-pounders, fifteen 32s, and eleven 24s; total in the fort, sixty-two. Just outside of and below the main work, covering the approach to it, was a water battery carrying one X-inch and two VIII-inch columbiads, and two rifled 32-pounders.[4] Of the guns in Jackson, the flanking howitzers and half a dozen of the 24- and 32-pounders could, from their position, have had little or no share in the battle with the fleet.