Following his trip abroad Roelfzema returned to Leiden University to continue his studies. When war broke out in Europe in September, 1939, Roelfzema and his fellow students supposed Holland would remain neutral as it had during the First World War. When the Soviet Union invaded Finland in November he traveled there to cover the conflict, working as a war correspondent for the , the and the . Afterwards he wrote a book about it, titled (The Smoldering Fire).