The Great War, or The Great European War (February 12, 1906 – December 24, 1909), was a major conflict occurring throughout Europe (and spilling over into its colonies in Africa and the Middle East) between 1906 and 1909. The war was the result of decades of tensions between the major powers in Europe. The war was the most expensive war at the time, and had one of the highest casualty rates in human history.