While travelling through Iran, one unit of the Polish troops encountered a young boy who was carrying a small malnourished bear cub, bought the cub from the boy, nursed it back to health, and named it Wojtek. Eventually, Wojtek (pronounced "VOY-tek") became the unit's unofficial mascot, learned how to smoke and drink beer, and stayed with the Polish army throughout the rest of the war, first in Palestine and then in Italy. Afterwards, with Poland under Soviet occupation and on its way to becoming a satellite of the USSR, Wojtek and some of his human comrades were reassigned to Scotland, where he lived out his years in the Edinburgh Zoo.
The above is the abridged version. Read the full story at Badass Of The Week. The life of Wojtek is also recounted in this YouTube video: