During the Civil War, West Tennessee College of Jackson was used first by the Confederate Army as a hospital and later by the Federal Army for camping grounds, the buildings for headquarters and as a hospital.

Like most schools in the South, West Tennessee College ceased to operate as a university for the duration of the war between the states. But it recovered quickly and reopened after the war with an even higher enrollment than before the war.

Murfreesboro was a different story. Only three miles away from the Stone's River battleground, the middle Tennessee campus felt the harsh impact of war. The school's only building was severely damaged; the library and apparatus completely destroyed. The federal government later reimbursed the university for damages done, but Union at Murfreesboro never fully recovered. A cholera epidemic in 1873 closed the campus down for good.

During World War I, it was not the war that was cruel to Union but nature itself. Now situated in Jackson, Tenn. (joined with the former West Tennessee College), Southwestern Baptist University became a student U.S. Army training camp in 1917. After almost a year of operation, the Army informed then Union President Dr. H.E. Watters that the University was to be represented at an officers' training school in Fort Sheridan, Ill. Just before the student officers could leave for Fort Sheridan, a vicious fire broke out in Adams Hall on Aug. 13. An epidemic of Spanish influenza soon followed.

Despite sickness and fire, Union prepared more than 200 young men for officer training camps. The government had tested this method of officer training on campuses throughout the country. The success of the program led the federal government to establish the Reserved Officer Training Corps. Union housed a military training program before World War I and was home to an active ROTC program on and off until 1976.

World War II had a similar rocky start at Union. By 1942, Union said goodbye to several of its faculty and staff who left university life to join military service. Attendance dropped off throughout the spring of that year, as well. The University eventually saw a total of 11 men die for their country, but in the long run World War II did prove to be a financially prosperous time for the University. By 1943, Union buzzed with military flying training. At the end of the second great war, over 1,200 cadets received at least a portion of their military flying training at Union.

In May of 1945, President John J. Hurt Sr. gave his final report to the Board of Trustees. In it he announced his retirement, the end of the university's indebtedness and a healthy endowment.

The Korean and Vietnam Wars would not have such a drastic impact on the University as that of the Civil War, World War I and World War II. During the Korean War, Union students serving their country were remembered by their fellow Unionites. The Cardinal and Cream diligently listed their service addresses in the student newspaper, and the C & C offered to mail its issues to students in the war. The Vietnam War did not go unnoticed but was not much debated either.