to a trade secret, this wine is also developed its qualities through a process which long remained a secret in underground cellars of the winery. Prized by the House of Habsburg, Tokay experienced profitable trading. Attempted imitation came to nought and the use of noble rot remained a secret. It was not until 120 years later that a method of very late harvest was experimented with on the steep banks of the Rhine. Its use in Sauternes was attested in 1836 in the Château La Tour Blanche but at that time very late harvest gave a very rich wine that required several years to age in barrels. Other regions were discovering secrets which would make them rich. So it was that Dom Perignon was the legendary creator of champagne. In a northern vineyard he developed a special wine that would give rise to an exceptional passion for wine produced in a climate where it could not be expected for wine to reach maturity nor sufficient colour. The fashion of drinking cheap dry white wine started in Paris in the 18th century. To evade the excise duty, Parisians took the habit of going to drink their wine at the producers premises outside the walls of the city. Cabarets opened their doors by the river, becoming Guinguettes (similar to taverns): so the wine that was drunk there was also called "guinguet". This is a wine from the hills of the Seine or the Marne, sour, but the conditions of transport of the time did not allow it to be used prematurely. Contemporary era Champagne was created in the 18th century but it was in the next century that its global expansion would occur. The crowned heads of Europe quickly made the wine stylish in their courts although its production, necessarily in bottles, made for a very expensive product. Historian Hugh Johnson assigns an important diplomatic role to champagne: Talleyrand would have offered this wine at the negotiating table of the Congress of Vienna, using it to relax his partners in the discussions. The occupation of Champagne by Russian troops in 1815 publicized the sparkling wine to the Russian aristocracy. The Veuve Clicquot (Widow Clicquot) booked her wine to her occupants saying "they drink today, tomorrow they will pay..." The progress of the glass industry (especially from the use of coal) helped to democratize the use of the glass bottle. The production of