On May 24, "brigadier general" Sickles was ordered to report back to Hooker. He was given command of Hooker's 2nd Brigade. Sickles saw his first major engagement at the Battle of Seven Pines. Sickles next saw action at the Seven Days Battles. Hooker's advance did not go well due in part to Sickles' brigade having difficulties moving through the swamps then meeting heavy Confederate resistance. When some of his men broke and ran to the rear, Sickles was only able to get a few to return. Nonetheless, Hooker's report noted Sickles gallantry in trying to rally his men. He did not stay long and missed the Second Battle of Bull Run and the Battle of Antietam, being in New York recruiting men for his brigade. When Ambrose Burnside replaced George B. McClellan as commander of the Army of the Potomac, both Hooker and Sickles were moved up to command larger units. Sickles still had hardly any battlefield experience yet was now leading Hooker's old second division of III Corps. Sickles was busy getting New York newspapers and Washington insiders to promote his image as a battle hardened fighting general.