Brooke's military career began when he joined the
4th Pennsylvania Infantry with the rank of
captain in April 1861. In August, he became
colonel of the newly raised
53rd Pennsylvania Infantry and served in the 1862
Peninsula Campaign. He temporarily commanded a
brigade during the
Battle of Antietam in September of that year. In May 1863, he was given permanent command of a
brigade of the 1st Division of the
II Corps, which he led in the
Battle of Chancellorsville and during the
Gettysburg campaign. On the
second day of the Battle of Gettysburg, July 2, 1863, Brooke found himself in the thick of the action when
Confederate lieutenant general James Longstreet launched his assault against the
Union lines south of
Gettysburg. Rushed into action as reinforcements by
Maj. Gen. Winfield Hancock, Colonel Brooke launched a limited
counterattack against oncoming Confederate forces with his brigade in the
Wheatfield. Although he was knocked out of action with a severe wound, his men temporarily stopped the Confederates and stabilized the Union line long enough to prevent a breakthrough. After recovery, Brooke subsequently also fought in the
Overland Campaign, including the
Battle of Spotsylvania Court House and other battles. He was promoted to
brigadier general of volunteers on May 12, 1864. General Brooke was critically wounded, again, at
Cold Harbor in June. Brooke led a division in western Virginia late in the war. He was promoted to
brevet major general in the volunteer army on August 1, 1864, for his service at Totopotomoy and Cold Harbor, and to brevet brigadier general in the
regular army on March 2, 1867, for Spotsylvania Court House. ==Later life==