Confederate boat expedition led by Commander J. T. Wood captured and destroyed USS Underwriter in the Neuse River, North Carolina.
Confederate submarine H. L. Hunley sank Union blockader Housatonic off Charleston -- the first submarine to sink a ship in combat.
Ships of Rear Admiral D. D. Porter's Mississippi Squadron moved up the Red River to commence the unsuccessful Army-Navy campaign to gain a foothold in the Texas interior.
CSS Albemarle , Commander J. W. Cooke, sank USS Southfield and forced the remainder of the Union squadron at Plymouth, North Carolina, to withdraw. Having gained control of the waterways in the area, the Confederates were able to capture Plymouth on 20 April.
USS Sassacus, Wyalusing , and Mattabesett engaged CSS Albemarle off the mouth of the Roanoke River as the Union sought in vain to regain control near Plymouth.
Confederate torpedo destroyed USS Commodore Jones in the James River, Virginia, one of several losses the Union suffered from torpedoes during the year.
The last of Rear Admiral Porter's squadron, after being trapped by low water, dashed through the hurriedly constructed Red River dams to safety below the Alexandria rapids.
USS Kearsarge , Commander J. A. Winslow, sank CSS Alabama , Captain R. Semmes, off Cherbourg, France, ending the career of the South's most famous commerce raider.
Rear Admiral D. G. Farragut's fleet steamed by Forts Morgan and Gaines, through the deadly torpedo field blocking the channel, and into Mobile Bay. In the fierce engagement with the forts and Admiral F. Buchanan's small squadron, Farragut won a victory worthy of his great name.
CSS Tallahassee , Commander J. T. Wood, put to sea from Wilmington, launching a brief but highly successful cruise against Northern shipping.
Fort Morgan, the last of the three forts at Mobile Bay to remain in Confederate hands, capitulated.
USS Wachusett , Lieutenant N. Collins, captured CSS Florida , Lieutenant C. M. Morris, at Bahia, Brazil. Thus, in the same year were the cruises of the dread raiders Alabama and Florida ended.
CSS Shenandoah , Lieutenant J. I. Waddell, commissioned off the Madeira Islands.
Torpedo launch commanded by Lieutenant W. B. Cushing destroyed ram CSS Albemarle in the Roanoke River, assuring the North of renewed control of the waters around Plymouth, North Carolina.
Confederate raiders captured small gunboats USS Key West, Tawah , and Elfin near Johnsonville on the Tennessee River.
Rear Admiral Farragut arrived in New York City, for a period of rest after his arduous duty in the Gulf of Mexico and was acclaimed as a conquering hero. Ten days later he was promoted to the newly established rank of Vice Admiral.
Flag Officer W. W. Hunter destroyed the last of the Confederate Savannah Squadron to prevent its capture by the advancing forces of General W. T. Sherman.
A joint Army-Navy operation under Rear Admiral Porter and Major General B. F. Butler unsuccessfully attempted to take the Confederate stronghold of Fort Fisher, Wilmington, by amphibious assault.