The regiment served in the Peninsula Campaign, and Tyler commanded the siege train of the Army of the Potomac under Maj. Gen. George B. McClellan. He received commendations for his participation in the Battle of Hanover Court House, the Battle of Gaines' Mill and the Battle of Malvern Hill. On November 29, 1862, Tyler was promoted to brigadier general of volunteers and under General Ambrose Burnside was assigned command of all the artillery in the "Center Grand Division" of the army. He was the second officer in the artillery to hold that position, the other being Henry Jackson Hunt. His guns participated in the Battle of Fredericksburg, providing artillery support for the series of assaults on Confederate positions on the heights near Fredericksburg.