Dogs in warfare have a long history starting in ancient times. From “war dogs” trained in combat to their use as scouts, sentries and trackers, their uses have been varied and some continue to exist in modern military usage.

War dogs were used by the Egyptians, Greeks, Persians, Sarmatians, Alans, Slavs, Britons, and the Romans. The Molossian 'Canis Molossus' dog of Epirus was the strongest known to the Romans, and was specifically trained for battle. Among the Greeks and Romans, dogs served most often as sentries or patrols, though they were sometimes taken into battle. The earliest use of war dogs in a battle recorded in classical sources was by Alyattes of Lydia against the Cimmerians around 600 BC. The Lydian dogs killed some invaders and routed others.
 
Often war dogs would be sent into battle with large protective spiked metal collars and coats of mail armor. Native Americans also used dogs as pack animals and to pull travois.
 
During the Late Antiquity, Attila the Hun used giant Molosser dogs in his campaigns. Gifts of war dog breeding stock between European royalty were seen as suitable tokens for exchange throughout the Middle Ages. Other civilizations used armored dogs to defend caravans or attack enemies. The Spanish conquistadors used armoured dogs that had been trained to kill and disembowel natives.
 
Later on, Frederick the Great used dogs as messengers during the Seven Years' War with Russia. Napoleon also used dogs during his campaigns. Dogs were used up until 1770 to guard naval installations in France.

The first official use of dogs for military purposes in the United States was during the Seminole Wars. The American Pit Bull Terrier was used in the American Civil War to protect, send messages, and as mascots in American World War I propaganda and recruiting posters.