Served on board the U.S.S. Cincinnati during the attack on the Vicksburg batteries and at the time of her sinking, 27 May 1863. Engaging the enemy in a fierce battle, the Cincinnati, amidst an incessant fire of shot and shell, continued to fire her guns to the last, though so penetrated by shellfire that her fate was sealed. Serving bravely during this action, Corcoran was conspicuously cool under the fire of the enemy, never ceasing to fight until this proud ship went down, "her colors nailed to the mast."