As regimental commander, he served in the Peninsula Campaign in the Second Division, VI Corps, Army of the Potomac. Bidwell apparently was not present at the Battle of South Mountain or the Battle of Antietam. In 1863, when VI Corps, under Maj. Gen. John Sedgwick, crossed the Rappahannock River during the campaign culminating in the Battle of Chancellorsville, Bidwell’s regiment served in the brigade of Brig. Gen. Thomas H. Neill in the Second Division, VI corps, now under Brig. Gen. Albion Howe. The 49th New York distinguished itself by fending off probing attacks launched by Confederate MG Jubal Early as Neill's brigade approached Fredericksburg, Virginia. Bidwell thereafter was involved in the Second Battle of Fredericksburg and the Battle of Salem Church. On the morning of May 4, 1863, Bidwell's regiment, with artillery support, fended off an attack by the 48th Virginia Infantry from the brigade of Brig. Gen. William "Extra Billy" Smith. The New Yorkers reported capturing 200 prisoners and the colors of that regiment. The 49th New York suffered only 35 casualties in these actions. Bidwell continued in regimental command at the Battle of Gettysburg, where he served under General Neill on the far right flank of the Army.