The present-day Macedonian people have lived on the Balkan Peninsula since the Slavic settlement of Southeast Europe in the 6th and 7th centuries. Their history was overshadowed and forgotten after the Berlin Congress of 1878. Based on unpublished documents from the German Empire, the continuous identity of the Macedonians is demonstrated. Reports from German missions prove that the claims still made by neighboring countries on the Macedonian name, language, and territory stem from the era and spirit of imperialism. At the same time, the documents reveal how closely the events surrounding the Balkan League were linked to the intrigues of the Entente that led to the outbreak of World War I.