Cool pup, he would warn soldiers about mustard gas or enemy forces sneaking up on a position, or, kind of like Tyrone Slothrop, hearing the dog-whistle sounds of missiles in the air. Via National Geographic: Some 20,000 dogs did duty for the Allies, carrying equipment on their backs and messages concealed in their collars, laying telephone lines, and distributing first aid kits.
At the Battle of Verdun, Satan, a black greyhound-collie mix, saved a besieged French garrison by delivering a message, despite being severely wounded by gunfire.
One of the most courageous canines was Stubby, a U.S. combat dog. (See: Sergeant Stubby, by Ann Bausum.) A Boston bull terrier cross with bug eyes and a short, stubby tail that gave him his name, he'd never have made it at Westminster or Crufts.
He started life as a stray, roaming the streets of New Haven, Connecticut. One morning in 1917, he wandered into Yale Field, where a group of soldiers was being trained. Pvt. J. Robert "Bob" Conroy took a shine to him, and a bond was formed. Conroy prepared to ship out to the killing fields of France with the 102nd Infantry, 26th Division, known as the Yankee Division.
It was strictly against Army regulations to take pets on a troop ship, but Conroy, in a show of Yankee ingenuity, enlisted the aid of a crew member on the U.S.S. Minnesota who hid the dog in an engine-room coal bin. When they reached France, Conroy carried Stubby off the ship concealed in his overcoat.