When Germany invaded the Sudetenland in western Czechoslovakia, the British Government followed a policy of appeasement which it had employed throughout the 1930s, and signed the Munich Pact. This allowed Germany to legally annex the Sudetenland; however, they did not stop there and set their sights on further expansion in central Europe.

When Germany invaded Poland on 1 September, 1939, Britain stood by its promise to defend Polish borders and declared war on Germany two days later. Mobilisation of troops was slow though, and Poland fell within a month. Fearing the threat posed to its citizens, the British Government launched Operation Pied Piper on 1 September. Over the course of three days, 1.5 million vulnerable people, such as children, pregnant women and disabled people, were evacuated out of the target areas into the reception areas in the countryside.

The British Expeditionary Force was sent to France for training, and a phase of inactivity began, known as the ‘Phoney War’. In the Spring of 1940, Germany then turned its sights on Denmark and Norway in the north and Luxembourg, Belgium, and the Netherlands in the west. Germany invaded France in May 1940, and the British Prime Minister Neville Chamberlain was replaced by Winston Churchill. In the same month the Local Defence Volunteers, later known as the Home Guard, was formed. Comprising men usually too young or too old for military service, it would be Britain’s last line of defence during an invasion. The German invasion of France culminated in the BEF being evacuated from the beaches of Dunkirk between late May and early June 1940. The Royal Navy was assisted by civilian vessels affectionately referred to as ‘the little ships of Dunkirk’. Over 338,000 British and French soldiers were rescued at Dunkirk, and a further 14,000 were rescued from Le Havre and St Valery-en-Caux later in June. 70,000 men, however, were left behind in France.

Within a couple months, Germany had captured much of northern and western Europe using what they called Blitzkrieg, or lightning war. Suddenly, the invasion threat was a very real prospect for the British Government and public. On 10 July, 1940, the Battle of Britain began over Southern England. The German air force, known as the Luftwaffe, began a campaign of destruction against the Royal Air Force, aiming to gain air superiority over RAF and limit its ability to defend Britain against invasion. The RAF resisted the attacks and scored a decisive defensive victory, with the Battle of Britain coming to an end in late October 1940.

Before the battle ended, Germany changed tactics. Beginning 7 September, the Luftwaffe conducted a massive bombing raid on London, marking the beginning of the Blitz. Towns and cities across Britain, usually close to industrial centres and areas of production, were badly hit. By the time the Blitz had ended on 11 May 1941, scores of people had lost their homes, and over 43,000 civilians were killed. Although the heaviest phase of aerial bombing was over, the British public were not totally safe, and bombing raids continued. Towards the end of the war, Germany began to use the V1 and V2 rockets. These long-range missiles, known as ‘revenge weapons’, were just as much a psychological weapon as they were physical, aiming to erode the British public’s morale.

British and Allied forces were battling the Axis in the desert too. An iconic victory came during the Second Battle of El Alamein between October and November 1942. This represented the first major victory on land for British forces during the war, and represented a shift in the North African Campaign, which would end with an Allied victory in May 1943.

In July 1943, the Allies launched an amphibious landing in Sicily, followed by an invasion of mainland Italy in September. British forces played a pivotal role right up to the end of the Italian Campaign in May 1945, with battles such as Anzio and Monte Casino written into British military history.

Plans for an Allied invasion of North-West Europe began to take shape in 1943. On 6 June, 1944, D-Day arrived. After months of planning for an operation codenamed Operation Overlord, US, British, Canadian and other Allied forces stormed five beaches along the heavily fortified coast of Normandy, France. British forces were assigned ‘Gold’ and Sword’ beaches, in addition to landing airborne troops behind enemy lines. The invasion was a success, and the Allies now had a foothold in France. With fierce fighting, Allied Forces moved into France, arriving in Paris by late August 1944, in the face of stiff resistance. The Germans were now in retreat and the Allies could continue to push forward.

Allied forces continued to advance across occupied Europe. With a final offensive, German forces attempted to resist the Allied invasion. For almost six weeks, neither side gained ground in the Battle of the Bulge. The forested Ardennes made it difficult to advance, but the Allies were victorious, eventually crossing the River Rhine in late March 1945 and began a march toward Berlin. During this time, Allied forces discovered the atrocities of the Holocaust. They learned of the mass killings and internment of Jews, ethnic minorities, Soviet citizens, and many other groups against whom Hitler discriminated.

In April 1945, Soviet forces arrived in Berlin, and Hitler committed suicide. Without a leader and with enemies on all sides, Germany unconditionally surrendered to the Allies on 7 May, 1945, and came into effect the following day.

In the backdrop to the war in Europe, British and Allied forces were engaged in fighting with Japan in the Pacific and Far East, after Japan attacked Pearl Harbour on 7 December 1941, bringing the United States into the war. British territorial possessions soon fell to the Japanese onslaught, including Singapore on 15 February 1942. A staggering 130,000 British and Commonwealth prisoners are estimated to have been captured during the fighting in Singapore and Malaya. British forces fought bravely on the land, sea and in the air, and were engaged in a long campaign in Burma (now Myanmar) throughout the war in the Far East. Victories during the battles of Imphal and Kohima turned the tide of the campaign in favour of the Allies, who retook Burma the following year. The Allies called for Japan’s unconditional surrender with the Potsdam Declaration on 26 July, 1945, warning that the alternative was prompt and utter destruction. When the Japanese refused, the US detonated two atomic bombs in the country within three days of each other, one at Hiroshima and the other at Nagasaki. Japan announced its surrender on 15 August 1945, with the official surrender coming on 2 September. 15 August is now known as V-J Day (Victory in Japan Day).

It is estimated that Britain lost 384,000 members of its armed forces during the war, in addition to 70,000 civilians killed. Tens of thousands of British personnel were held as prisoners of war by Germany and Japan.