On March 9, 1864, Ulysses S. Grant was promoted to the rank of lieutenant general, and given stewardship of the Armies of the United States. Grant understood that it would be necessary to defeat Lee’s army if he was to end the war. As a result many of the final battles of the war would play out in Virginia. In June of 1864 at Cold Harbor, outnumbered Rebels entrenched themselves in strong earthwork fortifications, and rode out each successive Yankee assault. More than 10,000 Union soldiers were lost in the fighting along the Cold Harbor line between May 31 and June 12.