The prominent general leading the Union Army during the American Civil War was Ulysses S. Grant. Starting as a general early in the conflict, Grant's strategic approach and leadership led to significant victories, including the capture of Vicksburg, which was pivotal in controlling the Mississippi River. Appointed as General-in-Chief in 1864, he executed a strategy of total war against Confederate fortifications, ultimately leading to the surrender of General Robert E. Lee at Appomattox Court House in 1865. Grant's leadership and victory played a crucial role in preserving the Union and shaping the future of the United States.