Which battle of 732 halted the Umayyad advance into Europe?

Tours, or Poitiers - and Gibbon's line about how, without it, Oxford might now be teaching the Quran has given the battle a weight modern historians largely reject. The force Charles Martel met was probably a large raiding expedition rather than an invasion aiming at Paris.

What is not contested is what it did for the Franks. Martel's prestige from the victory let his family displace the Merovingian kings; his son Pepin took the crown, and his grandson was Charlemagne. The battle matters as the foundation of the Carolingian dynasty more clearly than as the salvation of Christendom.

The Umayyad advance had already reached its practical limits. Supply lines from Iberia across the Pyrenees were long, the caliphate was overextended from Spain to Central Asia, and it was hit by the Berber revolt and then the Abbasid revolution within twenty years. Al-Andalus itself lasted another seven centuries and produced Cordoba, which was for a period the largest and most learned city in western Europe.