After the Civil War began, he was appointed by President Lincoln as a leader of a volunteer regiment. He impressed President Lincoln with his leadership skills and his aggressiveness, and was promoted to General, where he continued to excel and help lead the Northern Union Forces to victory over the Southern Confederacy. Grant's effective military leadership included victories in the Battles of Shiloh and Vicksburg. He was considered, by Northerners, to be an American hero. The Civil War came to a conclusion when Union General U.S. Grant met with the commander of the Confederate Forces, General Robert E. Lee at the Appomattox Courthouse in Virginia, to accept Lee's and the Confederacy's surrender to end the war.
Note: There are just a handful of photographs of Grant, Lincoln, and soldiers from the Civil War, as photography had only recently been invented, and cameras and people who could reliably operate them, were scarce. The most famous photographer from that period was a man named Mathew Brady. (for more about Mathew Brady, see
https://en.wikipedia.org/wiki/Mathew_Brady)