The Twelfth Battle.

About The Twelfth Battle: the Caporetto Campaign 1917, from BoardGameGeek:

The Twelfth Battle is a solitaire wargame that simulates the Central Powers offensive in Italy that began on October 24th, 1917, with an all-out assault around the town of Caporetto. Using gas and stormtroopers, German and Austro-Hungarian formations assaulted the Italian defensive lines along the Isonzo River and around the town of Caporetto, creating a huge breach in their positions. Hundreds of thousands of Italian troops, demoralized and fatigued from the first eleven attritional battles along the Isonzo, were made casualties or surrendered. In this game, you play as the Central Powers forces and must attempt to achieve a level of success exceeding that which they were able to historically obtain.