Tercio

The tercio was a Spanish infantry formation of the sixteenth and seventeenth centuries that combined pikemen, swordsmen and arquebusiers in large, disciplined squares. It made the armies of the Spanish Empire among the most formidable in Europe. Accounts of the Swedish Empire note that Gustavus Adolphus reformed this model by breaking the tercio's massive squares into smaller, more manoeuvrable brigades of musketeers and pikemen.