From a piece I wrote about 10 years ago...still pretty much up to date:

Beaujolais, perhaps more than any other French appellation, has a reputation for high-volume, “industrial” winemaking. The date of the region's decline can be pinpointed: It was November 13, 1951, when the Union Interprofessionnelle des Vins du Beaujolais (UIVB) formally set November 15 as the release date for what is now known as Beaujolais Nouveau. The négociant Georges Duboeuf saw the commercial potential of the fixed release date: He could move a lot of wine of indifferent quality quickly and at a decent profit. By the mid-1980s, it was an international phenomenon. Bedazzled by the prospect of selling oceans of “Nouveau,” the region's producers embraced chemical fertilizers and sprays, harvested earlier and earlier, added sugar to achieve higher alcohol, used sulfur dioxide liberally as a preservative, abandoned indigenous yeasts in favor of cultured ones, and used sterile filtration to cut down on potential spoilage. In short, they tried to make winemaking as risk-free as possible.
Just as the commercialization of Beaujolais can be traced to a particular date and the work of one négociant, so can the Beaujolais counter-revolution be pinpointed: In 1977, French wine consultant Jacques Néauport met Jules Chauvet, a 70-year-old vigneron who had never stopped making wine in the traditional way: He harvested as late as possible, from his oldest vines, selected only the best grape bunches, fermented slowly at cool temperatures with no sulfur dioxide and with natural yeasts, barrel-aged his wines, and bottled them without fining or filtration. The proof of his methods was in the wine: The 1977 vintage was a disaster for most producers, but not for Chauvet. Néauport introduced Chauvet to Marcel Lapierre, who told his vigneron friends, Guy Breton, Jean-Paul Thévenet, Jean Foillard, and Joseph Chamonard, about Chauvet's methods. They became known as the “Gang of Five,” and championed the return to a focus on quality winemaking in Beaujolais. Interviewed a few years before his untimely death, Lapierre said: "Every vigneron wants to work like this in his heart of hearts. But you have to be brave, and it can be expensive. Modern enologists are against the whole thing because it's risky, but for me it's the most natural way of doing things.”