It will be difficult to determine company but not regiment.

Battery 1 , AKA the redan, was contructed along the Tennessee shore, not on Island Ten itself. Commanded by Capt Edmond W Rucker of the "Stewart Invincibles", Battery 1 included three 8-inch Columbiads and three 32-lb smoothbores. Since the first attack on March 15th, only the Columbiads had been fired at the Federal fleet: smoothbores had no effect on at the long ranges involved. Guns had been mounted on an iron platform, now under a sheet of water as the river flowed into the battery. Ammuntion had to be stored on the top of the parapet beside each gun. High water also forced sentinels to stand guard on top of the parapet, the main guard being posted behind the redan at night.

Having to work in knee-deep water, Rucker's Tennessee artillerymen were supported by detachments from the 1st Alabama Regiment. Men from the Alabama regiment carried ammunition to the parapet from dry ground behind Battery 1. At night the artillerymen rested behind the back wall of the redan while sentinels watched over the Mississippi River from that part of the parapet still above water.

On the night of April 1st Admiral Foote sent an expedition of five boats to spike Rucker's guns. Led by Col George W Roberts of the 43rd Illinois, the expedition consisted of ten sailors from each of the ironclads except the "Carondolet", and fifty soldiers from the 43rd Illinois. About dusk rain began to fall. By 11:00 PM as the men in the five boats neared their objective, a great storm struck the Madrid Bend area. The two sentinels could see nothing in the rain and darkness until a flash of lighting revealed boats in the river a short distance away. Both men fired and made their way to the main guard camped behind the redan's rear wall.

While Roberts and men men spiked each of the guns and disabled their carriages, the officer in charge of the main guard sent for reinforcements. By the time these had been assembled and moved forward, Roberts and his men had returned to their boats. Battery 1 was effectively removed from immediate service to the Confederate defense of Madrid Bend.

Before the damage could be assessed, men on both sides took cover as tornadoes caused further destruction in the area. During the early morning hours trees fell in encampments of both sides. Among other incidents of the night, an officer of the 7th Illinois Cavalry and two men were killed, and the Federal transport "Kanawha Valley" capsized in the river.

Taken from Larry J Daniel and Lynn N Bock, Island No. Ten: Struggle for the Mississippi Valley, p. 120.

Capt R A Stewart and his Pointe Coupee Artillery had been in action on March 9th. On this day Federal troops occupied Point Pleasant along the Missouri shore below New Madrid. Capt Stewart opened fire with two 10-lb Parrott rifles stationed on the opposite side of the Mississippi. After New Madrid was evacuated on March 15, 1862, General Beauregard ordered a several Confederate units to Fort Pillow. Eight transports left on March 18th, followed by three more the next day. Among the many commands leaving Madrid Bend was the Pointe Coupee Artillery.
Island No. Ten, pp. 52 and 95.

The unit under discussion was at Fort Pillow during the attack on April 1st. The map below shows positions of most Confederate defenses. New Madrid is just above on the Missouri shore --