faster by cross-breeding with American bison in a separate breeding project in Munich, in 1934. World War II Heck gained the support of then Reichsjägermeister Hermann Göring, who hoped for huntable big game. Heck promised his powerful supporter in writing: "Since surplus bulls will soon be set, the hunting of the Wisent will be possible again in the foreseeable future". Göring himself took over the patronage of the German Professional Association of Wisent Breeders and Hegers, founded at Heck's suggestion. Kurt Priemel, who had since resigned as president of the International Society for the Preservation of the Wisent, warned in vain against "manification". Heck answered by announcing that Göring would take action against Priemel if he continued to oppose his crossing plans. Priemel was then banned from publishing in relation to bison breeding, and the regular bookkeeper of the International Society, Erna Mohr, was forced to hand over the official register in 1937. Thus, the older society was effectively incorporated into the newly created Professional Association. After the Second World War, therefore, only the pure-blooded bison in the game park Springe near Hanover were recognised as part of the international herd book. 1950s onwards The first two bison were released into the wild in the Białowieża Forest in 1929. By 1964 more than 100 existed. Over the following decades, thanks to Polish and international efforts, the Białowieża Forest regained its position as the location with the world's largest population of European bison, including those in the wild. In 2005-2007, a wild bison nicknamed Pubal became renowned in southeast Poland due to his friendly interactions with humans and unwillingness to reintegrate into the wild. As of 2014 there were 1,434 wisents in Poland, out of which 1,212 were in free-range herds and 522 belonged to the wild population in the Białowieża Forest. Compared to 2013, the total population in 2014 increased by 4.1%, while the free-ranging population increased by 6.5%. Bison from Poland have also been transported beyond the country's borders to boost the local populations of other countries, among them Bulgaria, Spain, Romania, Czechia and others. Poland has been described as the world's breeding centre of the European bison, where the bison population doubled between 1995 and 2017, reaching 2,269 by the end of 2019 – the total population has been increasing by around 15% to 18% yearly. In July 2022 a small population was released into woodland in Kent