The Atlanta Campaign began on 6 May 1864. Sherman had over 100,000 men he divided into three field armies. Johnston's army was only about half the size of the Union army facing him. Sherman used his larger army in a series of battles to push Johnston back. He used two of his armies facing Johnston's Army of Tennessee. The third army was used in flanking maneuvers. Finally, Johnston retreated into Atlanta on July 9–10. Johnston's strategy had been to "trade space for men and time". He would not commit his army to a major battle but delayed and harassed Sherman every chance he got. It took Sherman 72 days to march his armies only 100 miles. Johnston's plan was to slow down and wear out the Union army and make them tired of fighting. But Jefferson Davis, the Confederate president, dismissed Johnston for not stopping the Union army. He gave command to John B. Hood, Johnston's second in command.