Toward the end of the Civil War, Union strategists turned their attention to capturing Wilmington, North Carolina, one of the last effective Confederate ports. Located about twenty-eight miles up the Cape Fear River, the city was guarded by the nearly impregnable Fort Fisher at the mouth of the Atlantic Ocean. Late in December 1864 a joint Union Army and Navy attack commanded by General Benjamin F. Butler and Admiral David Dixon Porter failed to inflict any substantial damage on the port, but the assault was renewed in January 1865 by General Alfred Terry and Admiral Porter. The Union Fleet, which consisted of sixty warships including the New Ironsides and four monitors, was the most powerful naval attack force then assembled. The second bombardment of the fort commenced on the morning of January 13 and continued until the Confederate defenders capitulated at 10:00 on the fifteenth. The surender of Fort Fisher ended the last major naval engagement of the Civil War.