This picture is during the WW1, the British Army made dogs pull machine guns and ammo that weigh up to 150 pounds. Dogs where used for many different things, they carried aids to the wounded carried for ammo, they also sent messages or got trained to be a watch dog. New under cover records show that over 20,000 canines where trained to do different duties during WW1. Some of these dogs came from dog homes, police forces or even just family pets. Watch dogs would never bark but would growl to indicate someone was approaching.