Served as quartermaster 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 although so penetrated by enemy shell fire that her fate was sealed. Conspicuously gallant during this action, Hamilton, severely wounded at the wheel, returned to his post and had to be sent down below, to hear the incessant roar of guns as the gallant ship went down, "her colors nailed to the mast."