Already 65 at the outbreak of the Civil War, Adm. Forrest entered the U.S. Navy as a midshipman in 1811 and served throughout the War of 1812. He commanded the landing operations of Gen. Winfield Scott’s American army at Vera Cruz during the Mexican War, and from 1855 to 1856 he was the head of the Washington Navy Yard.

Resigning his commission after Virginia’s secession, Forrest joined the state navy of Virginia in April 1861 as a captain. He accepted a commission at the same rank in the Confederate navy in June, making him its third-ranking officer. He had commanded the navy yard at Norfolk while in Virginia service, and he remained in that position when he entered the Confederate navy. His primary task was the reconstruction of the scuttled USS Merrimack into the ironclad ram CSS Virginia. Forrest was replaced at Norfolk three months after the Battle of Hampton Roads to become the head of the Office of Orders and Details. There he was responsible for ensuring the flow of correspondence and orders within the Confederate Naval Department.

In March 1863 he took command of the James River Squadron. Frustrated by this squadron’s relative inactivity, Secretary of the Navy Stephen R. Mallory replaced him with Commdr. John K. Mitchell in May 1864. Since his name disappears from the roster of Confederate naval officers by June, he apparently was dismissed from service. After the war, he returned to his home in Alexandria, Virginia, and died in Washington, D.C., in November 1866.