Early in the morning of September 1, 1939, the German battleship Schleswig-Hoktein suddenly opened fire on Poland’s Westerplatte Peninsula. At the same time the Nazi Luftwaffe struck at Poland’s airfields, communication centres, economic and administrative centres, and the German army invaded its territory. By the end of 1941, the war had spread almost to the whole world. Could the Second World War have been prevented, the tragedy avoided? A reply to this question requires certain theoretical knowledge about war as a social phenomenon, and would call for an analysis of its causes and for an objective assessment of the events that preceded its outbreak.