I know I'm not amongst the first to hear about Sergeant Stubby, the pit bull hero of World War I, but I can't resist posting a link to a site where he is celebrated as the Badass of the Week. It's so amazing that at first I wondered how much of it was true. (Lots of swearing in the report, but what a humdinger of a story!)
I came across the reference to Stubby on The Pet Museum, where there's also another link, to an analysis of his story, on McSweeney. This second article seems more measured, as it explains some of the seemingly unbelievable exploits of Stubby in terms of known dog behaviours. For instance, the capture of a German spy near the American trenches may have occurred because Stubby, in making his rounds to look for wounded allied soldiers, smelled the fear on a disguised German soldier, and thus attacked him and held him for capture.
He saved many lives, it seems, through his superior canine senses. He could warn soldiers of incoming shells, by racing back to the trenches when he detected the high-pitched whine. He also warned of gas attacks before the humans could smell the mustard gas.
The McSweeney article has lots of other fascinating information about the role of dogs in war.