Seventy-five years ago, on 1 September 1939, Germany invaded Poland. With political agreements in place to come to Poland’s aid, Britain and France both declared war on Germany within two days. It was the start of a conflict that would erupt over every continent and see the deaths of tens of millions of people, with much of central Europe destroyed. It would also see the development of jets, intercontinental missiles, computers and the Atomic Bomb. 1939, in particular, saw the sinking of the passenger ship Athenia on the first day of the war, the evacuation of children from Britain’s population centres, the daring attack by U-49 on the Royal Oak at Scapa Flow, air raids on Wilhelmshaven and on Shetland and the Forth Bridge. It also saw the development of the Blitzkrieg tactics that were to prove so successful in France, Belgium and the Netherlands in 1940.