the Grand Dukes of Lithuania and later belonged to the Crown of the Kingdom of Poland. Polish-Lithuanian rulers took measures to protect the European bison, such as King Sigismund II Augustus who instituted the death penalty for poaching bison in Białowieża in the mid-16th century. Wild European bison herds existed in the forest until the mid-17th century. In 1701, King Augustus II the Strong greatly increased protection over the forest; the first written sources mentioning the use of some forest meadows for the production of winter fodder for the bison come from this period. In the early 19th century, after the partitions of the Polish Commonwealth, the Russian tsars retained old Polish-Lithuanian laws protecting the European bison herd in Białowieża but also turned all the people inhabiting the area into serfs. Despite these measures and others, the European bison population continued to decline over the following century, with only Białowieża and Northern Caucasus populations surviving into the 20th century. The last European bison in Transylvania died in 1790. Early 20th century During World War I, occupying German troops killed 600 of the European bison in the Białowieża Forest for sport, meat, hides and horns. A German scientist informed army officers that the European bison were facing imminent extinction, but at the very end of the war, retreating German soldiers shot all but nine animals. The last wild European bison in Poland was killed in 1921. The last wild European bison in the world was killed by poachers in 1927 in the western Caucasus. By that year, 48 remained, all held by zoos. The International Society for the Preservation of the Wisent was founded on 25 and 26 August 1923 in Berlin, following the example of the American Bison Society. The first chairman was Kurt Priemel, director of the Frankfurt Zoo, and among the members were experts like Hermann Pohle, Max Hilzheimer and Julius Riemer. The first goal of the society was to take stock of all living bison, in preparation for a breeding programme. Important members were the Polish Hunting Association and the Poznań zoological gardens, as well as a number of Polish private individuals, who provided funds to acquire the first bison cows and bulls. The breeding book was published in the company's annual report from 1932. While Priemel aimed to grow the population slowly with pure conservation of the breeding line, Lutz Heck planned to grow the population