Lee's army, thinned by desertion and casualties, was now much smaller than Grant's. One last Confederate attempt to break the Union hold on Petersburg failed at the decisive Battle of Five Forks on April 1. The Union now controlled the entire perimeter surrounding Richmond–Petersburg, completely cutting it off from the Confederacy. Realizing the capital was now lost, Lee's army and the Confederate government were forced to evacuate. The Confederate capital fell on April 2–3, to the Union XXV Corps, composed of black troops. The remaining Confederate units fled west after a defeat at Sayler's Creek on April 6.