Raised in Ohio, young Grant possessed an exceptional ability with horses, which served him well through his military career. He was admitted to West Point and graduated 21st in the class of 1843. Grant served with distinction in the Mexican–American War. In 1848, he married Julia Dent, and together they had four children. Grant abruptly resigned his army commission in 1854 and returned to his family, but lived in poverty for seven years. During the Civil War, Grant joined the Union Army in 1861. Grant led the Vicksburg campaign, in 1863, which gained control of the Mississippi River. After Grant's victory at Chattanooga, President Abraham Lincoln promoted him to Lieutenant General. For thirteen months, Grant fought Robert E. Lee during the high-casualty Overland Campaign and at Petersburg. On April 9, 1865, Lee surrendered to Grant at Appomattox. A week later, Lincoln was assassinated and was succeeded by President Andrew Johnson, who promoted Grant to General of the Army in 1866. Later Grant openly broke with Johnson over Reconstruction policies; Grant used the Reconstruction Acts, which had been passed over Johnson's veto, to enforce civil rights for recently freed African Americans.