As morning broke on the 1st of September 1939 and the first invasion force of German troops crossed the Polish border, few could have imagined the sheer scale of devastation, misery and bloodshed that the following years of war would bring. World War II saw the mobilisation of over 100 million military personnel as all corners of the globe were thrown into a state of 'total war', where each nation involved drained every resource at their disposal - human, natural, economic, industrial and military. The result was the conflict to end all conflicts. With over 500 minutes of footage, this gripping documentary series covers all the major events, people and machinery involved in the 20th Century's most terrible conflict and examines the roles of all three branches of the armed forces - navy, air force and army.