In response to Nazi determination and concerted action to remove Jews from Europe by any means necessary, the non-Axis world closed many possibilities for emigration to other countries. For example, legal immigration to safety in Palestine, an area that had been assigned by the League of Nations as a Jewish homeland for Jews who were not safe in their original countries, was severely limited by the Mandate authorities in 1939; and many nations simply refused to allow European Jews entry to their countries. As Nazi Germany gained power and inherited larger Jewish populations in conquered territories (such as Poland) the policies in most nations were either to completely eliminate the Jewish presence (in the case of Axis countries) or to discourage Jewish immigration (in the case of non-Axis countries.) The closing of the immigration possibilities in America is covered by Wyman in his 1968 book "Paper Walls: America and the Refugee Crisis, 1938-1941". Wyman continues to document this aspect of World War II history in "The Abandonment of the Jews", which covers the period of 1941-1945, when America and the Allies fought against Germany and the Final Solution Holocaust progressed to its most lethal stages.