During the US Civil War Ulysses S. Grant commanded the Union army and Robert E. Lee commanded the Army of Northern Virginia which general refused to exchange prisoners?
Robert E. Lee surrendered to Ulysses Grant at the Appomattox Court House on Aril 9, 1865.
At times General Grant did refuse to exchange prisoners with the South. At other times he placed captured Confederates on parole. And, in the case of the surrender of Johnston at the end of the wat, he allowed General Sherman to negotiate a surrender.
During the US Civil War, the Union army was led by several generals. First was General in Chief Winfield Scott. After Scott retired, General George B. McClellan was appointed general in chief by President Lincoln. In 1862, Lincoln appointed General Henry W. Halleck as general in chief. In early 1864, Lincoln replaced Halleck with Lieutenant General US Grant.In the South, Confederate President Jefferson Davis ran the war. Finally in 1865, he appointed Robert E. Lee as the South's top general in chief.