Animals were widely used in all kinds of wars from the beginning of the times. It seems, the very first animal arms that served humans were ...bees. Our ancestors used to throw hives in the caves of not very friendly neighbours when the negotiations did not go in the right direction.
The list of the animals we used for these aims is long. There were 20 camels in Stalingrad, they transported cannons. Elks were used by secret services to reach enemies without noice. Infected flies, fleas, rats were thrown in the towns and fortifications from the airplanes in the modern times and with the cannons in the antiquity to win the enemies. Rattlemice with explosives were thrown from the airplanes: they entered under the roofs of the houses.
Did you know that the hens are very sensitive: they feel chemical substances in the air and the attentive owner can go out in time from the room if it becomes dangerous.
The light of the fireflys can be enough to read an important document.
I don't tell you about horses and elephants. And I would not tell you about dogs and dolphins if... If not an interessting peculiarity: they denied to kill. Well, dogs, used to explode the tanks, did it without intention. They were simply afraid of the roar of the tanks in the battles.
Dolphins and seals were used as real killers: they had needles tied to the noses. It was enough to touch a submariner to make him die. Seals were brave. But dolphins, seen that persons die, did not want to repeat it more.