The story
Wilhelm Mast founded Mast-Jägermeister SE (then a KG) in Wolfenbüttel in 1878. His son Curt Mast developed the recipe for the herb flavored 70-proof (35%) liqueur Jägermeister, which he first brought to market in 1935. Günter Mast was the managing director for many years until his death in 2011.
From Wikipedia’s article on Mast-Jägermeister, shared under CC BY-SA 4.0.5
