Under Charlemagne in the 8th century and the Carolingian emperors, Jews were official importers of exotic foods from the Holy Land; they also provided wine for Christian mass.
At the time, what did the rabbis write about the following matters?:
What were the halachic issues involved? Food issues? Basar b'chalav? Providing wine for use in a Christian religious ceremony?
And, in the end, did they allow or forbid the Jews to provide the wine?
(Related: a question which is not about historical responsa, but is about the practical halacha today regarding the wine question.)