When the reformers, captured by the National Socialists, returned to the Kulturbund in 1939, they exerted strong pressure on President Johann Keks and Giljum, under whom they resigned from their posts in August 1939. Sepp Janko became the new president of the movement. Giljum took over the management of the "German School Foundation" in October 1939, which sought to expand the German school system in Yugoslavia. After the German invasion of Yugoslavia, the organization expanded to Hungary, for which he moved to Budapest in 1942. In the winter of 1944, he fled the advancing Eastern Front to Linz, Austria.