  March of 1862, when both Lee and Grant were unknowns at this time.  Lee didnt assume command of the Army of Northern Virginia until  June 1862. Grant was a relative unknown when he won his first  victory at Fort Donelson in February, 1862, hardly enough time for  Tuco and Blondy to know who he was. That being said, in another  scene, Angel Eyes mentions Confederate abuses in Andersonville  Prison, which only became a prison in November 1863.