On May 7, 1864, 100,000 Federal troops under Sherman started south from Chattanooga, opposed by Joseph E. Johnston with 50,000 Confederates. Sherman relied more on flanking movements than battles to push the Confederates back. On June 19, Confederates entrenched at Kennesaw Mountain on an 8 mile front, and on June 27 Union attacks on Cheatham Hill and Little Kennesaw failed. On July 2, Sherman again executed a flanking movement, forcing the Confederates back toward Atlanta. On July 18, General Hood replaced Johnston. Atlanta fell on September 2 after 4 major battles in which Sherman's army gained control of roads and railroads into the city. On November 15, Sherman's army began the March to the Sea.