What was William Tecumseh Sherman's role in the war?

I am going to answer this question based on the assumption that you mean William Tecumseh Sherman, Union general during the Civil War.  Sherman was one of the most prominent generals of the Western Theater of the Civil War, having worked closely with Grant in the taking of Vicksburg, the final link the Confederates still possessed on the Mississippi River in 1863.  In 1864 Sherman was given a major campaign and his army marched from southern Tennessee to South Carolina, tearing railroads, telegraph lines, and anything else that the Confederacy might have of value.  His soldiers lived off the land and brought the misery of war home to the Deep South. Sherman's "March to the Sea" was one of the major factors that led to the end of the war.  Sherman's capture of Atlanta was a welcome piece of victory for the North at the time of Lincoln's re-election campaign in 1864.  After reaching the sea in South Carolina, Sherman then marched North, continuing to destroy vital supplies and infrastructure.  Sherman was going to link his army with Grant's before the final push to Richmond, but Lee surrendered to Grant at Appomattox Court House soon after Richmond fell to Union forces.  Sherman took the final surrender of the Army of Tennessee in North Carolina soon after Richmond.