Captain of a gun on board the USS Varuna during the attacks on Forts Jackson and St. Philip, and while under fire and ramming by the rebel ship Morgan, 24 April 1862. During this action at extremely close range while his ship was under furious fire and twice rammed by the rebel ship Morgan, Greene remained steadfast at his gun throughout the thickest of the fight and was instrumental in inflicting damage on the enemy until the Varuna, badly damaged and forced to beach, was finally sunk.