Originally posted by crooktooth
Union of Churches, Union of Empires: Possible?
Actually, it may have been. Not by the dynastic ties suggested by Philip V (Otto, Zoe, etc.), but by force.
In 1025, at the death of the great Byzantine Emperor Basil II, the Churches were still united and the Byzantine army had established a solid dominance over its Slavic and Muslim foes. Basil II had crushed the Bulgars, retaken Antioch, and reduced the Muslim emirates of Syria to tributary status. Meanwhile, Italy was riven between feuding Lombard, Norman, and Italian mini-states. The Byzantines still had an Italian foothold at Bari. Had Basil's successors had the talent and the inclination, their well-prepared army could have swept up all of Italy south of the Po River without much trouble. The great project of Justinian would finally be completed, 500 years after his death.
The Byzantine Emperors were quite comfortable with bossing around high churchmen, and had imprisoned Popes before during their last occupation of Rome (from 540 to 700 AD). If they had re-occupied Rome, they could have forcibly prevented the Schism, and also stopped the Popes from crowning the German Emperors.
That's probably the best-case scenario. A Byzantine annexation of the German lands of the HRE would be very unlikely (Byzantium never tried extending its power away from the Mediterranian basin). The reverse scenario, a German annexation of Byzantium, would likely have played out similarly to the Fourth Crusade; an overextended military occupation of hostile territory, eventually lost to native dynasts.
But the moment passed. When Basil II died, the throne passed through his niece Zoe to her three husbands, none of whom had any talent. The state and the army were left to drift. Meanwhile, the declining Arab emirates facing the Byzantines were refashioned by the invading Seljuk Turks into a unified, dynamic state. At Manzikert in 1071 the Turks wiped out the decayed Byzantine thematic army, and Byzantium forever ceased to be a major military force.
