5.7% During the first years of the Oktoberfest, the Bavarian brewing law from 1539 stipulated that beer could only be brewed between the “Michaeli” or St. Michael’s day on September 29 and St. George’s feast day, April 23. It was forbidden to brew in the summer because the boiling process was considered a fire hazard. Moreover, bottom-fermented beer needs a temperature between 4–6°C for fermentation. Of course, no one wanted to forgo the pleasures of beer drinking in the summer, so a surplus quantity was brewed. And such are the origins of the beer known as Märzen. The last beer brewed at the end of the brewing season was given a higher gravity to increase its shelf life, since Märzen beer was to be sold throughout the summer and during the fall’s folks festivals. - Hacker-Pschorr Brewery