The 45th Division (or Thunderbird Division) landed in North Africa, 22 June 1943, and trained at Arzew, French Morocco. It landed in Sicily, 10 July, in its first major amphibious operation and moved inland under minor opposition. The enemy resisted fiercely at Motta Hill, 26 July, before losing the fourday battle of "Bloody Ridge." On 1 August, the Division withdrew for rest and patrols. On 10 September 1943, the second landing at Salerno occurred. Against stiff resistance, the 45th pushed to the Calore River, 27 September, crossed the Volturno River, 3 November, and took Venafro.

Until 9 January 1944, the Division inched forward into the mountains reaching St. Elia north of Cassino before moving to a rest area. The 45th landed at Anzio, 22 January 1944, and for 4 months stood its ground against violent assaults. It went over to the attack, 23 May, crossed the Tiber River, 4 June, outflanking Rome and withdrew for rest and training on the 16th.

The 45th participated in its fourth assault landing, 15 August 1944, at St. Maxime in Southern France. Against slight opposition, it spearheaded the drive for the Belfort Gap. It took the strongly defended city of Epinal, 24 September, crossed the Moselle River and entered the western foothills of the Vosges, taking Rambervillers on the 30th, and crossing the Mortagne River, 23 October.

After a brief rest the 45th cracked the forts north of Mutzig, an anchor of the Maginot Line, 25 November, crossed the Zintzel River and pushed through the Maginot defenses. From 2 January 1945, the Division fought defensively along the German border, withdrawing to the Moder River. On 17 February, it went back for rest and training.

The 45th moved north to the Sarreguemines area and smashed at the Siegfried Line, 17 March, taking Homburg on the 21st and crossing the Rhine between Worms and Hamm on the 26th. The advance continued, Aschaffenburg falling, 3 April, and Nurnberg on the 20th. The Division crossed the Danube, 27 April, took Munich on the 30th and as war ended was stationed near Dachau.