After the outbreak of World War I, the regiment saw action on the Western front, where Prince Heinrich was badly wounded. Upon recovering, he returned to his old infantry regiment and in June 1915, was promoted to Major. At the same time, he was put in charge of the III. Battalion of the newly established Deutsches Alpenkorps stationed in the Carnic Alps. In late 1916, the battalion was transferred to Romania where it fought at Turnu Roşu Pass. On 7 November 1916, during operations in the area near Poiana Spinului, while conducting a personal reconnaissance of the front line, his life was claimed by Romanian rifle fire.