On February 6, 1862, Dana was appointed brigadier general, to rank from February 3, 1862, and given command of the 3rd Brigade of the 2nd Division in the Union II Corps, a brigade consisting of volunteer soldiers from New York, Massachusetts, and Michigan. Dana led this brigade throughout the Peninsula Campaign in the spring and summer of 1862, participating in the Siege of Yorktown in early April to early May, the Battle of Seven Pines in late May and early June, the Battle of White Oak Swamp on June 30, the Battle of Glendale also on June 30, and the Battle of Malvern Hill on July 1.