Since 1933, Germany had been ruled by Adolf Hitler and his political party, the Nazis. They wanted to take revenge for Germany’s defeat in the Great War by expanding Germany’s empire.
In 1938, the Nazis invaded Austria and on 15th March 1939 they invaded Czechoslovakia.
Next, on 1st September 1939, over a million Nazi troops then invaded Poland. The UK and France had promised to help the Poles if they were attacked so gave Hitler an ultimatum (final demand) by threatening war if his troops did not withdraw by 3rd September. Hitler ignored this threat and so war was declared.
Most families in the UK heard the news on the radio, announced by the Prime Minister, Neville Chamberlain at 11:15am. He told them, “This country is at war with Germany”.
World War II was fought between two major alliances (groups of countries), which at the start of the war were:
The Germans quickly invaded Denmark and Norway (April 1940), Luxemburg, the Netherlands and Belgium (both in May) and then conquered France by June. The Allies tried to disrupt them but failed. Chamberlain was replaced by Winston Churchill as Prime Minister of the United Kingdom in May 1940 because the British were unhappy with his work.
In June 1941, The Soviet Union then joined the Allies, after Germany attacked it. On December 11, 1941, four days after Japan carried out a huge attack on the American naval base at Pearl Harbor in Hawaii, the United States also joined the Allies. The war had become global.
Some countries did not join the war but stayed neutral (on neither side). They included: Spain, Sweden and Switzerland. Ireland was also a neutral country though many Irish people still helped the Allies.
The 1939 National Services (Armed Forces) Act forced all males between 18 and 41 who weren't working in a reserved occupation (e.g. dock workers, bakers, scientists, railway workers and utility workers – water, gas, electricity) were called up to do National Service and fight for their country.
From 2nd December 1943 onwards, 48,000 men were also sent to work in the coal mines to help fuel the war effort. They were known as ‘Bevin Boys’, named after the then minister of Labour and National Service, Ernest Bevin.