Numbers 20. Report of Captain Alfred P. Rockwell, First Connecticut Battery.

JAMES ISLAND, June 17, 1862.

SIR: I have the honor to report, for the information of the commanding general, the part taken by the First Light Battery, Connecticut Volunteers, in the attack yesterday upon the enemy at Secessionville, S. C.

In compliance with orders received from Brigadier-General Stevens, commanding Second Division, the two sections of the First Connecticut Battery were ready to move at 2.30 o'clock in the morning. The section of 12-pounder howitzers, under command of Lieutenant S. E. Porter, took its place in the First Brigade immediately in rear of the Seventh Connecticut Regiment; the remaining section, under command of Lieutenant S. E. Porter, took its place in the First Brigade immediately in rear of the Seventh Connecticut Regiment; the remaining section, under command of Lieutenant William T. Seward, immediately in rear of the First Brigade, and all moved forward with the column. On reaching the causeway the rifled section was halted by order to allow the Second Brigade to pass by. It then moved forward in the rear of this brigade. The howitzer section on reaching the field moved obliquely across the field in rear of the two advancing regiments as rapidly as the extremely uneven surface of the ground would admit, and took up a position on the left of the Eighth Michigan Regiment at a point about 500 yards from the Tower, and opened fire upon the enemy's earthworkd very soon after the enemy had commenced firing. In the mean time the rifled section had arrived upon the field and was advancing regiments as rapidly as the extremely uneven surface of the ground would admit, and took up a position on the left of the Eighth Michigan Regiment at a pint about 500 yards from the Twer, and opened fire upon the enemy's earthwork very soon after the enemy had commenced firing. In the mean time the rifled section had arrived upon the field and was advancing to the support of the pieces already in position, when orders were received to send forward one piece only, and that I would plant the other piece in the road to protect the left flank. I accordingly sent the one piece, under command of Lieutenant Seward, to support Lieutenant Porter. He joined him, and the three pieces kept up a constant fire until after the infantry had fallen back to the hedge. The pieces were then withdrawn in good order to the road. Here the two sections took position and opened fire upon the enemy's works at a distance of about 1,500 yards, firing constantly and regularly until after the enemy's guns had ceased to answer.

When the infantry were again moved forward on our right the howitzer section, in obedience to orders, advanced to support them, with instructions to fire canisters. They took up a position and maintained it under a heavy fire of grape, canister, and solid shot from the enemy's earthworks, at a distance of from 400 to 500 yards, until the retreat was ordered. The rifled section was soon ordered up to support the howitzers, and accordingly moved rapidly forward.

Finding upon examination that I had fired away nearly all my ammunition I sent Lieutenant Seward back to camp for a fresh supply, which arrived on the ground just after the retreat tot he wood had been effected.

The four pieces continued firing from the advanced positions which they held until the retreat was ordered. It was here that I had 4 horses killed. The retreat was effected in good order, one piece at a time, so as not to give the enemy a point to concentrate his fire, to the corn field in the rear of the wood, where the battery was ready to move in any direction ordered.

While preparation was being made to plant the pieces on the line of the road a further retreat was ordered, and the battery moved off and took up position near the causeway, supported by cavalry, to cover the retreat should the enemy advance. Subsequently we moved back to camp, leaving one section at the headquarters of the reserve pickets.