 Complete the following phrase:  The Marine Corps played a small role in the Civil War 18611865; their most prominent task was blockade duty. As more and more states seceded from the Union, about a third of the Corps officers left the United States to join the Confederacy and form the Confederate States Marine Corps, which ultimately played little part in the war. The battalion of recruits formed for the First Battle of Bull Run performed poorly, retreating with the rest of the Union forces. Blockade duty included sea-based amphibious operations to secure forward bases. In late November 1861, Marines and sailors landed a reconnaissance in force from at Tybee Island, Georgia, to occupy the Lighthouse and Martello Tower on the northern end of the island. It would later be the Army base for bombardment of Fort Pulaski. In April and May 1862, Union Marines participated in the 