Colonel William Irwin’s 6th Corps brigade of Maj. Gen. William F. “Baldy” Smith’s 2nd Division was an experienced unit, whose regiments were mustered into service between May 9, 1861, and November 23, 1861. They participated to varying degrees in all combat during the Peninsula Campaign and Seven Days Battles.
Pennsylvanian William Howard Irwin was born in 1818 and attended Dickinson College for two years before returning home to study for the bar. He entered the Army in February 1847 and received a commission in the 11th U.S. Infantry. Irwin was seriously wounded at the Battle of El Molino del Rey on September 8, 1847, during the war with Mexico, while leading his company. He received a brevet to major for his bravery and returned to Pennsylvania to practice law until the outbreak of the Civil War when he again donned a uniform. He enlisted as a private after the fall of Fort Sumter but quickly rose to the rank of colonel of the 7th Pennsylvania Volunteers, a 90-day unit that participated in the early advance on the Shenandoah Valley in June–July 1861.
After the regiment mustered out, Irwin assisted in raising and organizing several Pennsylvania units. He was appointed colonel of the 49th Pennsylvania in late 1861. Several of his subordinates brought charges against him for drunkenness and “conduct prejudicial to good
