Doubleday, Abner soldier, born in Ballston Spa, New York, 26 June 1819, was a civil engineer in 1836'8, when he was appointed to the U. S. military academy, and on his graduation in 1842 was assigned to the 3d artillery, He served in the 1st artillery during the Mexican war. being engaged at Monterey and at Rinconada Pass during the battle of Buena Vista. He was promoted to 1st lieutenant, 3 March 1847, to captain, 3 March 1855, and served against the Seminole Indians in 1856'8. He was in Fort Moultrie from 1860 till the garrison withdrew to Sumter on 26 Dec. of that year, and aimed the first gun fired in defense of the latter fort on 12 April 1861. He was promoted to major in the 17th infantry on 14 May 1861, from June till August was with General Patterson in the Shenandoah valley, and then served in defense of Washington, commanding forts and batteries on the Potomac. He was made brigadier general of volunteers on 3 February 1862, assigned to the command of all the defenses of Washington on the same date, and commanded a brigade on the Rappahannock and in the northern Virginia campaign from May till September 1862, including the second battle of Bull Run, where on 30 August he succeeded to the command of Hatch's division.

In the battle of Antietam his division held the extreme right and opened the battle, losing heavily, but taking six battle flags. On 29 November 1862, he was promoted to major general of volunteers. He was at Fredericksburg and Chancellorsville, and succeeded General John P. Revnoldsaschief of the 1st corps when that officer was appointed to the command of one wing of the army. On 1, July 1863, he was sent to Gettysburg to support Buford's cavalry, and, on the fall of General Reynolds, took command of the field until the arrival of General Howara, some hours later. His division fought gallantly in the battle that followed, and on the third day aided in the repulse of Pickett's charge.

General Doubleday served on courts-martial and commissions in 1863'5, and on 12 July 1864, temporarily commanded the southeastern defenses of Washington when the City was threatened by Early's raiders. He was brevetted colonel in the regular army on 11 March 1865, and brigadier and major general on 13 March for his services during the war. In November and December 1866, he was in command at Galveston, Tex., served as assistant commissioner of the Freedman's bureau there till 1 August 1867, and, after being mustered out of the volunteer service, was made colonel of the 35th infantry, 15 September 1867. He was a member of the retiring board in New York City in 1868, and in 1869'71 superintended the general recruiting service in San Francisco, where in 1870 he suggested and obtained a charter for the first cable Street railway in the United States.

After commanding posts in Texas he was retired from active service on 11 December 1873. He has published" Reminiscences of Forts Sumter and Moultne in 1860'1" (New York, 1876); "Chancellorsville and Gettysburg" (1882): and articles in periodicals on army matters, the water supply of cities, and other subjects.