the president of MIT, he would receive one of the first radiographs in the country, which documented the extent of the damage to his hand. He did not return to service until August 1863. Walker participated in the Bristoe Campaign and narrowly escaped encirclement during the Battle of Bristoe Station before withdrawing and encamping near the Berry Hill Plantation for much of the winter and spending some leave in the North. After extensive reorganization during the winter of 1863–1864, Walker and the Army of the Potomac fought in the Overland Campaign through May and June 1864. The Battle of Cold Harbor in early June took a substantial toll on the ranks of the II Corps and Walker injured his knee during the battle. In the ensuing Richmond-Petersburg Campaign, Walker was appointed a brevet colonel. However, on August 25, 1864, as he rode to find Maj. Gen. John Gibbon at the front during the Second Battle of Ream's Station, Walker was surrounded and captured by the 11th Georgia Infantry. On August 27, Walker was able to escape from a marching prisoner column with another prisoner but was recaptured by the 51st North Carolina Infantry after trying to swim across the Appomattox River and nearly drowning. After being held as a prisoner in Petersburg, he was transferred to the infamous Libby Prison in Richmond, where his older brother was also held. In October 1864, Walker was released with thirty other prisoners as a part of an exchange. Walker returned to North Brookfield to recuperate and resigned his commission on January 8, 1865, as a result of his injuries and health. At the end of the war, Maj. Gen. Winfield Scott Hancock recommended that Walker be brevetted as a brigadier general of U.S. Volunteers in recognition of his meritorious services during the war and especially his gallant conduct at Chancellorsville. On July 9, 1866, Walker was nominated by President Andrew Johnson for appointment to the honorary grade of brevet brigadier general, U.S. Volunteers, to rank from March 13, 1865 (when he was age 24), for gallant conduct at the battle of Chancellorsville and meritorious services during the war. The U.S. Senate confirmed the appointment on July 23, 1866. After the war, Walker became a companion of the Massachusetts Commandery of the Military Order of the Loyal Legion of the United States. Based upon his experiences in the military, Walker published two books describing