The Mexican–American War helped to train generals that would later be in which war?

The Mexican–American War, which took place from 1846 to 1848, helped to train many generals who would later be involved in the American Civil War (1861-1865). Some of the notable generals who gained experience and leadership skills during the Mexican–American War and went on to play crucial roles in the Civil War include Ulysses S. Grant, Robert E. Lee, Stonewall Jackson, and George McClellan.