in 1863 mexico asked which us president for help
President Abraham Lincoln
Ulysses S. Grant
 After Grant's victory at Chattanooga, President Abraham Lincoln promoted him to Lieutenant General. 
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Ulysses S. Grant [SEP] Introduction
military academy in 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, he joined the Union Army in 1861, and led the Vicksburg campaign, which gained control of the Mississippi River in 1863. 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.