Beauregard was unhappy with his new assignment, believing that he deserved command of one of the great Confederate field armies. He performed successfully, however, preventing the capture of Charleston by Union naval and land attacks in 1863. On April 7, 1863, Rear Admiral Samuel Francis Du Pont, commander of the South Atlantic Blockading Squadron, led a union ironclad attack against Fort Sumter that was repulsed by highly accurate artillery fire from Beauregard's forces. In July through September 1863, union land forces under Brig. Gen. Quincy A. Gillmore launched a series of attacks on Fort Wagner on Morris Island and other fortifications at the mouth of the harbor, while Rear Adm. John A. Dahlgren attempted to destroy Fort Sumter. Because the latter operation failed, the successful seizure of Morris Island was not effective in threatening Charleston.