Wine had become indelibly written on the Mediterranean way of life. But there was no stability north of the Alps. In the face of waves of cruel invaders, the settled arts - vineyards among them - were in deep peril. Only the Church, with its need for wine and its power to organize and confer continuity, kept the vines growing. As Europe emerged into recorded history again, it was around the monasteries and cathedrals that vines were to be found.
The monks did more than make wine: they improved it. The medieval Cistercians of Burgundy were the first to study the soil of the Cote d'Or, and to transform vineyards by selecting the best vines, experimenting with pruning, and choosing plots without frost and in which grapes ripened best. They built walls around the best vineyards: the clos which still survive, if in name only, are testimony to the keen-eyed monks of centuries ago. An outpost of Cistercians at Kloster Eberbach did the same thing in the Rheingau. All this effort was to make wine not just for the Mass, but for the market: the monks were a central part of the medieval wine trade.
Medieval life gradually became more settled, allowing the expansion of vineyards and the revival of trade in wine. Wine had never entirely died out as a trading commodity: the pirate-filled western seas of the Dark Ages had seen merchant ships creeping from Bordeaux or the Rhine's mouth to Britain, Ireland and further north. The meanest barbarian chief felt that his station called for wine at feast-times, the remotest hermit needed wine for the Sacrament.
With restored trade came the great wine-fleets: hundreds of ships at a time plying to London or the north German ports. Rivers became important trade routes: wine casks are heavy and cumbersome, and waterborne transport suits them best.
For medieval man, wine or beer was not a luxury but a necessity. Cities had impure - often dangerous - water supplies. Wine was an antiseptic, a component of the primitive medicine of the time. It was added to water to alleviate its endemic pollution. Water was rarely drunk by itself, in cities at least. "Water is not wholesome sole by itself, for an Englishman," wrote Andrew Boorde, an English scholar, in 1542.
Large quantities of wine were traded. Bordeaux's exports to England in the -14th century were so great that the average annual total was not exceeded until 1979. Edward 11 of England ordered the equivalent of over a million bottles to celebrate his wedding to Isabella of France in 1308. Under Elizabeth I almost three centuries later the English were drinking over 40 million bottles of wine a year. The population at the time was 6.1 million.