The 90th Infantry Division was activated in summer 1917, just months after the United States entered World War I. It participated in several military campaigns in France. During World War II, the "Tough Ombre" division landed at Utah Beach on D-Day (June 6, 1944) as part of the massive Allied invasion of western Europe. After pushing through northern France, the unit advanced into the Saar region of Germany, but was redeployed to Belgium during the German offensive into the Ardennes (the Battle of the Bulge). The 90th returned to Germany and captured the city of Mainz on March 22, 1945. Several days later, the "Tough Ombre" division crossed the Rhine and subsequently moved southward into Bavaria and then eastward into Czechoslovakia.
On April 23, 1945, the 90th overran the Flossenbürg concentration camp, finding about 1,500 prisoners who had not been evacuated on death marches. The unit's journal recorded that one of its motorized patrols entered the camp that day and found "a serious typhus epidemic" in "full swing." The troops interviewed the surviving inmates, who estimated that Flossenbürg had held some 16,000 prisoners before the SS guards evacuated the camp on April 20. The SS had forced the prisoners to work in a nearby stone quarry and in a Messerschmitt plane factory, making fighter craft for the German air force.
After liberating Flossenbürg, the 90th discovered more evidence of Nazi atrocities as they advanced farther. Just prior to the camp's liberation the SS guards had forced some 14,000 inmates to march southward. The 90th and other army divisions found some 6,000 of these prisoners alive. They also discovered the bodies of more than 5,000 inmates, who had died from exhaustion or starvation or had been killed by the SS guards because they failed to keep up with the pace of the march.
The 90th Infantry Division was recognized as a liberating unit by the US Army's Center of Military History and the United States Holocaust Memorial Museum in 1985.
Casualty figures for the 90th Infantry Division, European theater of operations:
- Total battle casualties: 19,200
- Total deaths in battle: 3,951
Called the "Tough Ombres," the 90th Infantry Division was raised from draftees from the states of Texas and Oklahoma during World War I. The divisional insignia incorporates the letters "T" and "O" to symbolize both states. These letters later yielded the nickname "Tough Ombres," symbolizing the esprit de corps of the unit. The 90th was also sometimes called the "Alamo" division during World War II.