from "What Do Dogs Know?":
dogs know it or not, they often rely more upon instinct
than upon knowledge or education. During World War
II, the Nazis stationed along the Maginot Line used
dogs as messengers. The French soidiers tied to
shoot these dogs, but they were difficult to hit
because they moved so quickly and silently.
One French dog handler then
tried an experiment, releasing a small female French
messenger dog who had just gone into heat. As she
had been taught, the French dog returned to her
post later that evening.Trailing behind her were
nearly a doren normally obedient German Army dogs
who had discovered something much more powerful
than their milItary training.