By their looks, the soldiers in the photo are probably reservists, born 1897-1900, and called up in August, 1939. The photo could be from the winter of 1939-40, during the lull in the hostilities known as “the Phoney War”. Some of the men could be WW1 veterans if they turned 20 years old before that war ended. They were probably conscripted before the limitations of the Treaty of Versailles went into effect, but it’s possible that some of them are Zwölfenders, soldiers who had signed on for 12 years in the 100,000-man Reichswehr. On average, slightly less than 5 % of those year classes died in the war, indicating that most of them served in second line units or as occupation troops.