Homing pigeons were used extensively during WWI. Carrier pigeons were trained to transport messages back to their home coop behind the lines. When they landed, wires in the coop would sound a bell or buzzer and a soldier would know a message had arrived. He would retrieve the message from the canister, and send it to its destination by telegraph, field phone, or personal messenger. In 1914 during the First Battle of the Marne, the French army advanced 72 pigeon lofts with the troops. The US Army Signal Corps used 600 pigeons in France alone. One of their homing pigeons, a Blue Check hen named Cher Ami, was awarded the Croix de Guerre with Palm for heroic service delivering 12 important messages during the Battle of Verdun. On her final mission in October 1918, she delivered a message despite having been shot. The crucial message, found in the capsule hanging from a ligament of her shattered leg, saved about 200 US soldiers of the 77th Infantry Division's "Lost Battalion".
