Pirenne first expressed ideas on the formation of European towns in articles of 1895;Pirenne, "L'origine des constitutions urbaines au Moyen Age", in Revue Historique, 1895. he further developed the idea for the Pirenne Thesis while imprisoned in Germany during World War I. He subsequently published it in a series of papers from 1922 to 1923 and spent the rest of his life refining the thesis with supporting evidence. The most famous expositions appear in Medieval Cities: Their Origins and the Revival of Trade (1927, based on a series of lectures of 1922) and in his posthumous Mohammed and Charlemagne (1937), published from Pirenne's first draft.Henry Pirenne (1937). Mohammed and Charlemagne English translation by Bernard Miall, 1939. From Internet Archive. The thesis was originally laid out in an article published in Revue belge de Philologie et d'Histoire 1 (1922), pp. 77–86.
