At the beginning of their three week journey to Spain, from 23 June to 14 July 1938, Erika and Klaus Mann met the German commander, Hans Kahle, at the headquarters on the Ebro front close to Catalonian city of Tortosa. Kahle, a German journalist and editor who had become a member of the Communist Party in Switzerland in 1933 and later emigrated to France, made a great impression on the Mann siblings. At the beginning of the Civil War Kahle, along with the writer Ludwig Renn as his Chief of Staff, had been the Commander of the 11th International Brigade - the German Thälmann Brigade, and he now commanded a division of 14,000 soldiers.

On June 27, Klaus and Erika Mann met with Ludwig Renn and Hans Kahle and together with Renn they visited a military school. In the following days in Barcelona, prior to their onward journey to Valencia and Madrid, they encountered other émigrés such as the Austrian Social Democrat Julius Deutsch as well as Ernst Busch and Erich Weinert. Erika Mann felt especially connected to Hans Kahle with whom she spent a long evening of "cognac, cigarettes and talk." After their return, both Erika and Klaus published reports about "Colonel Hans" in the Neue Volkszeitung, a German-language weekly published in New York, and in the party newspaper of the Prague Social Democrats, Sozialdemokrat.