Shortly after coming to America , he was appointed visiting professor of German history at Yale .
Unwilling to participate in National Socialism , that same year he fled to the United Kingdom , then emigrated to the United States in 1934 .
Shortly after coming to United States , he was appointed visiting professor of German history at Yale .
Unwilling to participate in National Socialism , that same year he fled to the United Kingdom , then emigrated to the United States in 1934 .