A Mongol-Christian military alliance against Islam was genuinely planned and nearly happened

Evidence

It had its culmination in a series of Mongol embassies to the West between 1285 and 1290, which came for the express purpose of preparing for a joint attack on Islam. These embassies were led by Nestorian Christians, and in 1287 there was the unexampled spectacle of the leader of the Mongol embassy attending Mass in St. Peter’s, in the presence of the Pope. What a vista of endless and universal peace and unity was opened up by this picture: Islam, either destroyed or, better still, converted by philosophy; the Mongol empire stretching to the confines of China, a Christian state; and Christendom itself enriched by the philosophical tradition handed down from Greece through Moslem philosophers, to provide the one thing necessary for the fullness of Christian truth. It was a noble prospect, and one which, if only a fraction of it had come true, would radically have altered the history of the world. — R. W. Southern, Western Views of Islam in the Middle…, 381

Categorization

• QUESTION: Worth chasing: what exactly prevented the Mongol-Christian joint attack on Islam — was it internal Mongol succession crisis or Western inertia?
• XREF: Connects to the reader’s earlier curations on medieval Islam-as-trade-institution and on reputation/trust across civilizations.
• SEED: A ‘what-if’ piece on the planned 1287 Mongol-Christian alliance and the world history that hung on its failure.

Related

• Latin Christians sought Mongol alliances against Islam as anti-Muslim strategy (similarity 0.82)
• Islam blocked the papacy’s hoped-for reunion with the Mongols (similarity 0.82)
• Mongol contact revealed Christian-Islamic agreement and unknown eastern Christians (similarity 0.80)
• Medieval Europeans pursued Mongol alliances against Islam until Mongol conversion dashed those hopes (similarity 0.79)
• The Mongols’ appearance transformed the Western world picture of Islam (similarity 0.78)
• By 1220 Christians projected apocalyptic victory onto real Mongol conquests (similarity 0.78)
• Anti-Muslim ideologues simultaneously courted Muslim allies when politically useful (similarity 0.78)