Robert Sanford Foster was an American officer. He served as a Union general during the American Civil War. He played a prominent role in the Siege of Petersburg and the Appomattox Campaign.

The Appomattox campaign was a series of American Civil War battles fought March 29 – April 9, 1865, in Virginia that concluded with the surrender of Confederate General Robert E. Lee's Army of Northern Virginia to forces of the Union Army under the overall command of Lieutenant General Ulysses S. Grant, marking the effective end of the war.