Pleasonton, Alfred, 1824–97, Union general in the American Civil War, b. Washington, D.C. He served in the Mexican War and in the Indian wars on the frontier. In the Civil War, he distinguished himself in the Peninsular campaign (1862) and was made brigadier general of volunteers. He fought at Antietam and Fredericksburg, and his stand against Stonewall Jackson at Chancellorsville averted a total Union defeat. He commanded the Union cavalry at Brandy Station and in the ensuing Gettysburg campaign, as well as later engagements. Transferred to Missouri, Pleasonton defeated Gen. Sterling Price at Westport and Marais des Cygnes (1864), ending the last Confederate threat in the West.