The German invasion of Poland on September 1, 1939, came just one week after Nazi Germany had signed a neutrality pact with the Soviet Union.
It meant that Poland ended up being bombarded from all sides by two vastly more powerful hostile powers – with Russian troops invading the country on September 17.
Hitler’s decision to invade Poland was a gamble; partly because the German Army – the Wehrmacht – was not yet at full strength, and partly because German generals were unsure how Britain and France would react.
German soldiers are pictured celebrating the occupation of Westerplatte with the erection of a swastika on September 7, 1939
But Hitler himself regarded British Prime Minister Neville Chamberlain and French leader Edouard Daladier to be weak and indecisive and thought they would opt for peace rather than declare war.
However, the Nazi leader’s annexation of Czechoslovakia in 1938, which Hitler’s previous promise that he had no future territorial demands in Europe, prompted Chamberlain to formally guarantee Poland’s borders in the face of aggression.
And a defence treaty between Britain and Poland also added weight to signals that Britain might react offensively to more German aggression.
But, once Hitler had the political support of Italian dictator Mussolini, he felt he had the capability to carry out his plans and felt Britain’s defence pledge would amount to little.
It was then that the invasion of Poland began on September 1, with fierce attacks coming through bombing raids, land invasions and naval bombardments.
Poland immediately requested military assistance from Britain and France and two days later the two countries declared war on Germany.
However, despite the declaration, Britain and France had little offensive strategy and were caught entirely unprepared for the speed with which German forces invaded Poland.
The country was therefore forced to face the overwhelmingly superior Nazi Germany, and later the Soviet Union, on its own.
The Luftwaffe – the German air force – overwhelmed Polish air capability and armoured divisions on land easily pushed through Polish defences.
Warsaw, the capital, surrendered to German forces on September 27, 1939, and the last Polish resistance were defeated on October 6.
Polish citizens suffered enormously, with the bombing of Warsaw killing up to 25,000 and millions more dying throughout Germany’s occupation of the country.