Cats have taken part in war since ancient times, although their use was often more gruesome than heartwarming. In the 20th century, though, we had quite a few morale-boosting stories of cats that made the global news during the two World Wars, like this one from 1918 of a cat who changed sides.
A story of a cat is told in British letters from the front. The lookout men saw a cat emerge from the German trenches in front of them, make her way calmly to their trenches, pass through, and proceed to the rear, where she carefully inspected the officers’ billets. Then she retraced her steps to the German lines and the Englishmen supposed they had seen the last of her. To their amazement she re-appeared with a kitten in her mouth, passed by them to the zone of comparative safety in the rear, dropped her kitten in the dugout, went back to the German trenches and got kitten number two. Finally she had three kittens safe in the English lines. Speculation as to the reason for her removal of the kittens was in vain. She never told why she deserted the Germans.