Benjamin Huger , James Longstreet , and A.P .

Longstreet 's and Hill 's attacks Attack penetrated the Union defense Defending near Willis Church .

In moving Motion units to shore up the supposed gap , Rosecrans accidentally created Creating an actual gap , directly in the path of an eight-brigade assault Attack on a narrow front by Confederate Lt. Gen. James Longstreet , whose corps had been detached Removing from the Army of Northern Virginia .

In the resulting rout , Longstreet 's attack Attack drove Motion one-third of the Union army , including Rosecrans himself , from the field .