 Royalist army officer Agustín de Iturbide became an advocate of independence and persuaded insurgent leader Vicente Guerrero to join in a coalition, forming the Army of the Three Guarantees.Within six months of that joint venture, royal rule in New Spain collapsed and independence was achieved.The constitutional monarchy envisioned with a European royal on the throne did not come to pass; rather, creole military officer Iturbide became Emperor Agustín I.