What was Ulysses S Grant's role in the civil war?

Answer 1

He commanded the Union troops in Tennessee and Mississippi, culminating in the capture of Vicksburg, which ended the war in the West.

Together with his rescuing the Army of the Cumberland from starvation at Chattanooga, this gained him enough credibility to be promoted General-in-Chief of the US Armies, over the head of his commander, Henry Halleck.

He then divided responsibilities between himself and Sherman - Grant to defeat Lee, Sherman to defeat Joe Johnston. At enormous cost, Grant's objective was achieved, while Sherman masterminded an almost bloodless campaign in Georgia that shortened the war by months.

Answer 2

He played the principle role in the union defeat of the confederacy in the American Civil War.