A German soldier fought at Ypres in December 1914 during World War I. He was engaged in a confrontation against British Army Captain Archibald Hamish Lethbridge-Stewart. The man was wounded, having drawn his pistol on Lethbridge-Stewart in a shell hole, who did likewise with his service revolver. The two originally shot each other dead not long before the troops on either side came to a truce for Christmas Day.
However, the Twelfth Doctor used his TARDIS to send them forward in time to when the Christmas truce occurred. Because of such, both men stood down and joined the truce, Lethbridge-Stewart calling for first aid for the German soldier. (TV: Twice Upon a Time)