Originally Posted by dsj
During the middle ages I mean.
During the first 3 centuries AD and last two BC, I would vote for the Roman Legions and the Irish Fianna (who butchered the Roman Legions.)
In the Early Middle Ages the Huns were very effective defeating the Roman Legions forcing them to emply barbarian cavalry. The Byzantine Army was impressive in the 6th Century only to be swept away by the Ummayad Arab Light Cavalry of the 7th and 8th Centuries. In the 10th to 12th Centuries the Norman Knight controlled the battlefield until Agincourt when the Bowmen took prominence. Meanwhile the mounted Mongol mounted archers of the 13th Centuries were amost undefeatable. Then the Swiss Pikemen of the Habsburg Armies gained prominence until their defeat and annhilation at Rocroi. The Ottoman Sultanate's Armies using gun powder artillery, excellent cavalry, and the elite Jannissary Troops was dominant the 14th-17th Centuries.