Various material contemporary with the war have been used to compile The Great War:On This Day and associated index. Data has been gleaned from two main sources: Chronology of the War (1918-1920), and History of the Great War – Principal Events 1914-1918 (1922). The information in these works were deemed correct at the time of their respective publication dates, and may not accurately represent present-day histories, spelling of place names, political, and geographical boundaries. Click here for a full list of sources.