Arthur Pendleton Bagby, lawyer, editor, and Confederate general, was born in Claiborne, Monroe County, Alabama, on May 17, 1833, the son of Arthur Pendleton Bagby. The elder Bagby served in the Alabama state Senate and House of Representatives, where he was the youngest member ever elected speaker. He was also twice elected governor of Alabama, served in the United States Senate, where he supported the annexation of Texas, and was appointed United States ambassador to Russia by President James K. Polk.
The younger Bagby attended school in Washington, D.C., and the United States Military Academy at West Point. At age nineteen he became the youngest graduate to be commissioned a second lieutenant of infantry. He was stationed at Fort Columbus, New York, in 1852–53 and saw frontier duty at Fort Chadbourne, Texas, in 1853 with the Eighth Infantry, Eighth Military Department. He resigned to study law, was admitted to the bar in Alabama in 1855, and practiced in Mobile until 1858, when he moved to Gonzales, Texas. There he married Frances Taylor in June 1860.
Upon the eruption of the Civil War he joined the Confederate Army and raised the first company of men from the Victoria area for the cause. He served as a major, Seventh Regiment of Texas Mounted Volunteers, in Gen. Henry H. Sibley's Army of New Mexico. He was promoted to lieutenant colonel in April 1862 and later to colonel. On January 1, 1863, he led his regiment in the battle of Galveston, in which his "Horse Marines" assisted in the capture of the federal ship Harriet Lane. In this encounter Bagby won, according to Gen. John B. Magruder, "imperishable renown." Bagby later served under generals Richard Taylor and Thomas Green in western Louisiana, where he was wounded in fighting along Bayou Teche on April 13, 1863. For his service in Louisiana he was promoted for gallantry in action to brigadier general in early 1864 by E. Kirby Smith, although the rank was not approved in Richmond.
Nevertheless, Bagby's cavalry brigade, formerly Sibley's Brigade, in which Bagby served during the invasion of New Mexico in 1862, was one of the best mounted commands in the Trans-Mississippi Department. It consisted of the Fourth, Fifth, and Seventh Texas Cavalry and Waller's Thirteenth Texas Cavalry Battalion. In the Red River campaign at Mansfield and Pleasant Hill in 1864, Bagby also assumed command of Augustus C. Buchel's cavalry brigade, which consisted of the First and Thirty-fifth Texas Cavalry and Terrell's Texas Cavalry. Bagby commanded a brigade under Hamilton P. Bee in late April and early May 1864, before replacing Bee in command of the cavalry division in mid-May to harass the Union retreat. Following the surrenders of Lee and Johnston, Bagby was assigned to duty as major general on May 16, 1865, by E. Kirby Smith. He was placed in command of all cavalry forces in Louisiana and held that post until the surrender of the Trans-Mississippi Department. Bagby's latest promotion, however, was not approved in Richmond either. Thus Bagby was a general only as a result of a temporary appointment by Smith's headquarters.
After the war he settled in Victoria, Texas, resumed his law practice, and worked in 1870–71 as assistant editor of the Victoria Advocate. He later moved to Hallettsville, where he continued his law practice. He died there on February 21, 1921. Among his children, W. T. Bagby, also a lawyer, represented Lavaca County in the state legislature, where he earned the nickname "Lion of Lavaca" as an antiprohibition leader. He also figured prominently in the gubernatorial campaigns of Oscar B. Colquitt and James E. Ferguson. Another son, A. P. (Penn) Bagby, Jr., served as deputy tax collector and tax clerk of Lavaca County, chief clerk in the Texas secretary of state's office, and tax commissioner of the state of Texas under Governor James Ferguson.