The first preparatory steps for the war collection of the Deutsche Bücherei were taken in September 1914. Germany and France had mobilised and Great Britain had declared war on Germany. German troops had marched into Luxemburg, Belgium and France, while the Russians had entered East Prussia, and France had entered Lorraine. Brussels was occupied by the German troops and the Russian invasion had been resisted after the Battle of Tannenberg. 

In those weeks, questions arose about the extent of the new collection and its definition. Because the collecting guidelines laid out in the statutes of the library applied in principle to the war collection, exceptions had to be determined, which resulted from the course of the war itself. For example, how to deal with Russian notices that were posted in German areas, or those writings published by German authorities in conquered territories? 

In order to preserve as many traces of the war for coming generations, it was necessary to expand the spectrum of the collection. It was obviously possible to reach agreement quickly, as reflected in the Appeal of 12.10.1914: although at first postcards and special issues of daily newspapers were not requested, they were later included, as were food stamps, token money, photographs, war music. 

The collection strategy of letting down all boundaries and gathering together everything that was available was also pursued by other German libraries and institutions. Yet in contrast to them, the Deutsche Bücherei entered new territory with its collection and soon reached it limits of feasibility for a number of reasons, not least because of the abundance of the material. In the summer of 1917 it abandoned its original collection concept. The decision in favour of this turning point was taken internally and made known to the public only after the end of the war.