The 12th Armored Division was an armored division of the United States Army in World War II. It fought in the European Theater of Operations in France, Germany and Austria, between November 1944 and May 1945.

The German Army called the 12th Armored Division the "Suicide Division"for its fierce defensive actions during Operation Nordwind in France, and they were nicknamed the "Mystery Division" when they were temporarily transferred to the command of the Third Army under General George S. Patton, Jr., to cross the Rhine River.

The 12th Armored Division was one of only ten U.S. divisions (and only one of two U.S. armored divisions) during World War II that had African-American combat companies integrated into the division. One of the African American soldiers, Staff Sergeant Edward A. Carter, Jr. was awarded The Distinguished Service Cross for gallantry in combat during World War II, and was later awarded the Medal of Honor posthumously.

After completing training the division left Abilene and departed from Camp Shanks, New York, for the European Theater of Operations on 20 September 1944. It landed at Liverpool, England on 2 October 1944. While awaiting replacement armor which had been borrowed by the U.S. Third Army, the 12th was sent to Tidworth Barracks in Wiltshire, UK. It crossed the English Channel from Southampton, arrived at Le Havre, France, on 11 November 1944 and then traveled up the Seine River to Rouen to join the Seventh Army under Lieutenant General Alexander Patch. Advance elements met the enemy near Weisslingen in Alsace on 5 December, and the entire division moved against the Maginot Line fortifications two days later.

In its advance, Rohrbach-lès-Bitche and towns surrounding Bettviller were liberated by 12 December 1944, and Utweiler, Germany was seized on 21 December. After a short period of rehabilitation and maintenance, the 12th rolled against the Rhine bridgehead at Herrlisheim that the Germans had established as part of their Operation Nordwind offensive. In order to seal the Battle of the Bulge, units of the Seventh Army were diverted north to assist the Third Army in capturing Bastogne. Due to this, the remainder of the Seventh Army, including the 12th Armored Division, was stretched thin holding a 126 miles (203 km) long front line with only eight divisions.^[18]

German defenders repulsed two division attacks in the most violent fighting in the history of the division, during 8 to 10 January and 16 to 17 January 1945. The division's attacks at Herrlisheim failed to use combined-arms tactics and were defeated in detail, resulting in two tank and two armored infantry battalions taking heavy losses. Poor tactics were compounded by terrain that was almost tabletop-flat, offering the German defenders excellent fields of fire. However, enemy counterattacks failed also, in part because of the firm leadership of the commander of Combat Command B, Colonel Charles Bromley, who declared his headquarters expendable and ordered all personnel in the headquarters to prepare a hasty defense.

The division was subsequently relieved by the U.S. 36th Infantry Division. The 12th Armored Division suffered over 1,700 battle casualties during the fighting in and around Herrlisheim. As a consequence, when African-American soldiers who were in non-combat positions were able to volunteer to become combat troops, Major General Roderick R. Allen was one of only ten division commanders who allowed them to join the combat ranks.

After recovering from the bruising experience at Herrlisheim, the 12th went over to the offensive and attacked south from Colmar, after being assigned to the French First Army under General Jean de Lattre de Tassigny.^[20][21] In a lightning drive, the 12th effected junction with French forces at Rouffach, on 5 February, sealing the Colmar Pocket and ending German resistance in the Vosges Mountains. Except for elements acting as a protective screen, the division withdrew to the St. Avold area for rest and rehabilitation. The division was attached to the Third Army under General George S. Patton, Jr., on 17 March 1945 through its crossing of the Rhine on 28 March.^[ The soldiers were ordered to remove their identifying unit insignias and vehicle markings were painted over, disguising the fact that Patton had an additional tank division under his command. Thus the 12th was given the nickname the "Mystery Division". The attack resumed on 18 March 1945.

In a quick drive to the Rhine, Ludwigshafen fell on 21 March, and two other important river cities, Speyer and Germersheim, were secured on 24 March, clearing the Saar Palatinate. Maintaining the rapid pace, the 12th crossed the Rhine River at Worms on 28 March over pontoon bridges, advanced toward Würzburg, and captured that city along with elements of the famed 42nd Infantry Division (United States). After assisting in the seizure of Schweinfurt, the division continued toward Nuremberg on 13 April, taking Neustadt, then shifted south toward Munich on 17 April. Elements of the 12th raced from Dinkelsbühl to the Danube, where they found the bridge at Lauingen had been blown. Moving quickly they captured the bridge at Dillingen intact before demolition men could destroy it. This bridge provided a vital artery for Allied troops flooding into southern Bavaria.

The division spearheaded the Seventh Army drive, securing Landsberg, on 27 April and clearing the area between the Ammer and Würm Lakes by 30 April. The 12th Armored Division is recognized as a liberating unit of the Landsberg concentration camps near the Landsberg Prison, sub-camps of Dachau concentration camp on 27 April 1945. On 29 April 1945, the 12th AD liberated Oflag VII-A Murnau, a German Army POW camp for Polish Army officers interned north of the Bavarian town of Murnau am Staffelsee during World War II. 

Elements crossed the Inn River and the Austrian border at Kufstein on 3 May. The 12th Armored Division was relieved by the 36th Infantry Division on 4 May. On 5 May, Lieutenant (later Captain) John C. Lee, Jr., Co. B, 23rd Tank Battalion, organized the rescue of VIP French prisoners from an Alpine castle in Bavaria during the Battle for Castle Itter. Under Lee's command were members of the German Wehrmacht, who combined forces with 2 tanks from the 12th to fight the SS Commander and soldiers guarding the prisoners. For leading the successful rescue of these prisoners, Lee was promoted to Captain and awarded the Distinguished Service Cross.

The 12th Armored Division engaged in security duty around Ulm until 22 November 1945, when it left Marseille, France, for home. Some members of the 12th attended the US Army University, in either Biarritz, France or Shrivenham, England during this time.

It was deactivated on 3 December 1945, and on 17 December 1945, its battle flags were turned in at Camp Kilmer, New Jersey.