Andrew Atkinson Humphreys (November 2, 1810 – December 27, 1883), was a career United States Army officer, civil engineer, and a Union General in the Civil War who is best known for being a division commander of the III Corps of the Army of the Potomac during the Battle of Gettysburg. He also served in other senior positions in the Army of the Potomac, including division command and chief of staff, and he was Chief Engineer of the U.S. Army.
After the outbreak of the Civil War, Humphreys was promoted (August 6, 1861) to major and became chief topographical engineer in George B. McClellan's Army of the Potomac. He was promoted to brigadier general of volunteers on April 28 and on September 12 assumed command of the new 3rd Division in the V Corps of the Army of the Potomac. He led the division in a reserve role in the Battle of Antietam.
At the Battle of Chancellorsville, Humphreys' division was attacked by Colquitt's brigade on the 3rd day of the battle. On May 23, 1863, Humphreys was transferred to the command of the 2nd Division in the III Corps, under Maj. Gen. Daniel E. Sickles. On July 2, 1863, Sickles insubordinately moved his corps from its assigned defensive position on Cemetery Ridge. Humphreys' new position was on the Emmitsburg Road, part of a salient directly in the path of the Confederate assault, and it was too long a front for a single division to defend. Assaulted by the division of Maj. Gen. Lafayette McLaws, Humphreys' three brigades were badly mauled, and Sickles had pulled back Humphrey's reserve brigade to shore up the neighboring division under General Birney, which was the first to be attacked. Humphreys put up the best fight that could have been expected and was eventually able to reform his survivors on Cemetery Ridge, but his division and the entire corps were finished as a fighting force.
About half a year after the Battle of Antietam, Humphreys wrote his official account of the Battle of Antietam, focusing on the characterization of his division as too fatigued to fight and complaining about his division’s role in the battle. His account became part of The War of the Rebellion: Official Records of the Union and Confederate Armies. This edition of his account includes illustrations and maps of the Maryland Campaign, and it also includes pictures of the important commanders of the battle.
