In 1916, mobilization of the Commonwealth citizens occurred at Mt. Gretna for service on the Mexican Border. As troops began to come home, their mobilizations continued into the Great War, known today as World War I. The Pennsylvania division, now known as the 28th Division, was called up in the wake of America's entry into World War I. The division took part in six major campaigns in France and Belgium resulting in more than 14,000 battle casualties. With its entry into the war, the American forces helped turn the tide to the Allied victory. The 28th Division’s ferocity in combat earned it the title "Iron Division" from General John “Black Jack” Pershing, commander of the American Expeditionary Force.