The correct answer is B) He realized that they were outnumbered and ill-prepared.
General Johnston ordered the evacuation of Confederate troops at Jackson, Mississippi, upon hearing of the Union Army’s advance because he realized that they were outnumbered and ill-prepared.
Union General Ulysses Grant advanced to Vicksburg, Mississippi and then he decided to attack Jackson, Mississippi to eliminate the Confederated troops there. On May 14, 1863, General Ulysses Grant defeated the Confederated Army in the Battle of Jackson, Mississippi. Southern General Johnston ordered the evacuation of Confederate troops at Jackson, Mississippi, upon hearing of the Union Army’s advance because he realized that they were outnumbered and ill-prepared.