Why was William Tecumseh Sherman selected to command the Military Division of the Mississippi in 1864?

William Tecumseh Sherman was selected to command the Military Division of the Mississippi in March 1864 primarily due to his close and successful professional partnership with Ulysses S. Grant.1

Following their collaborative success in the Vicksburg campaign, where they effectively shattered Confederate defenses, the two generals' careers became inextricably linked as they worked toward a Union victory. When Grant was promoted to general-in-chief of the Union armies in March 1864, he entrusted Sherman with the command of the Military Division of the Mississippi, placing three armies under his authority. This appointment reflected the high level of trust Grant placed in Sherman’s strategic capabilities, which had been proven during their joint operations in the Chattanooga campaign in 1863.1