Zwieback is a form of rusk eaten in Poland, Germany, Scandinavia, Austria, France, Belgium, The Netherlands, Switzerland, Italy, Slovenia, Bosnia, Croatia, Serbia, North Macedonia, Bulgaria, Greece, and Turkey. It is a type of crisp, sweetened bread, made with eggs and baked twice. It originated in East Prussia. According to Fabian Scheidler, Albrecht von Wallenstein invented zwieback to feed his mercenary army during the Thirty Years' War. The Mennonites brought Zwieback to the Russian Empire; before the Russian Revolution, when many emigrated to the west, they brought Zwieback to Canada, the United States and other parts of the world.