 McClellan organized and led the Union 's army in the Peninsula Campaign ( also known as the Peninsular Campaign ) in southeastern Virginia from March through July 1862 . It was the first large @-@ scale offensive in the Eastern Theater . Making an amphibious clockwise turning movement around the Confederate States Army in northern Virginia , McClellan 's forces turned west to move up the Virginia Peninsula , with the Confederate capital , Richmond , as their objective . Initially , McClellan was somewhat successful against the equally cautious General Joseph E. Johnston , but the emergence of General Robert E. Lee turned the subsequent Seven Days Battles into a Union defeat . 
