The Cimmerians, a people of great bodily size, made war on Alyattes. He marched against them, and ordered his men to take into battle with them a number of large fierce dogs. When the dogs were released, they fell on the barbarians, as they would on a herd of wild beasts. They injured many of them, so as to disable them from action, and put the others to flight.
The Romans both faced and used dogs in battle. According to Wikipedia, ‘The Roman attack dogs were given metal armour covered in razor-sharp spikes, designed to force the enemy out of formation.’ Another source states that ‘...the Roman Army would routinely deploy its own War Dogs, with whole companies composed entirely of dogs’.
For the Middle Ages in Europe, there is much less information. Leaving aside the use of dogs by the conquistatores as it is the Early Modern period and outside Europe, the only citations I've found are in Jared Eglan's Beasts of War, which says
Mastiffs, as well as Great Danes, were used in England during the Middle Ages, where their large size was used to scare horses to throw off their riders or to pounce on knights on horseback, disabling them until their master delivered the final blow.
The same source also says:
The British used dogs when they attacked the Irish and the Irish in turn used Irish Wolfhounds to attack invading Norman knights on horseback.
What is not clear is whether these two references concern groups of dogs, or dogs which accompanied their masters into battle (i.e. the dogs fought individually, not as a group). Also, do these references relate to use in battle or just skirmishes?
That dogs were presented as gifts among nobles, and used for guard duty, hunting, scouting and chasing down fugitives is clear enough from various sources. There are also cases of individuals bringing their dogs to battle (e.g. Sir Piers Legh at Agincourt in 1415), but what I am interested in is groups (or ‘companies’ as cited above for Romans) of dogs in battle.
Were groups (or ‘companies’) of dogs used to attack enemy soldiers in battle in the Middle Ages in Europe?
Is it possible to cite any specific battles where this happened?
Or was it more a case of some nobles bringing their dogs into battle and these dogs fighting alongside their masters rather than as part of a group?