War Dogs have had a role in warfare since their domestication. For the purpose of this entry, we assign the war dog to the Roman Republic (240 B.C.) though Asia and even North America domesticated the dog as early as 10,000 B.C.
The concept of a war dog is an animal that is specifically trained for war to harass and attack the enemy. The war dog was usually highly trained for a period of years by competent trainers whose sole purpose was to breed these lethal animals, sometimes endangering themselves in the process. War dogs were led onto the battlefield by specialty handlers and the handlers would release the dogs on command.
Naturally, columns and formations of troops being attacked or harassed by a platoon of vicious attack dogs would more than likely break formation to repel them, softening the formation for the initial strike by infantrymen.