When the British prime minister Neville Chamberlain broadcast at 11am on Sunday September 3 that Britain was, again, at war with Germany, it came as no great shock to the people of Britain.

When the British prime minister Neville Chamberlain broadcast at 11am on Sunday September 3 that Britain was, again, at war with Germany, it came as no great shock to the people of Britain. Here Sam Clarke traces Britain's long road to war for the second time in little over 20 years.

During the lead up to World War II Britain, desperate to avoid another bloody war, had embarked on a long and patient series of negotiations with the recently re-militarised Nazi Germany. On September 15 1938, the British Prime Minister, Neville Chamberlain, met with the German leader, Adolf Hitler, in his mountaintop retreat at Berchtesgaden to discuss matters regarding Germany's continuing defiance of the Treaty of Versailles and its intentions to annex the Sudetenland, a mainly German inhabited area on the borders of Czechoslovakia.

In an effort to appease the German leader, Chamberlain agreed to allow Hitler to annex the Sudetenland, a move that was formally approved by the now famous Munich Agreement, signed by the leaders of France, Great Britain, Germany and Italy on September 30. It was also agreed at Munich that Germany be allowed to go no further in violating the Treaty of Versailles, signed by the powers at the end of the First World War.

Britain and France felt they needed to obtain an official agreement that Germany would take no further steps in breaking the treaty following a number of previous breaches. In 1935, Adolf Hitler had ordered a large scale German rearmament, something prohibited by the treaty, and the creation of an air force, the Luftwaffe, in defiance of the treaty.

On March 7 1936, Hitler had ordered troops of the Wehrmacht, the German armed forces, into the Rhineland. Although technically part of Germany, its proximity to France had led to it being declared a demilitarised zone by the Treaty of Versailles. Two years later, in March 1938, German troops had advanced into Austria and on March 12 had declared the Anschluss, or 'link-up' - a union also prohibited by the Treaty of Versailles.

Such blatant defiance of the accord reached at the end of the First World War were, however, more or less overlooked by the leaders of Britain and France, they chose instead to pursue a policy of appeasement in an attempt to avoid the atrocities of another war.

Nevertheless, by the time Hitler set his sights on the Sudetenland they felt some sort of limit had to be set on Germany's expansion while still pursuing a policy of appeasement.

On October 10 1938, the annexation of the Sudetenland agreed at Munich took place. For a while it looked as if Germany would now adhere to a signed agreement. Indeed it was at this point that Chamberlain waved his famous piece of paper signed at Munich and declared: “there will be peace in our time.”

But, on March 15 1939, Hitler and his Hungarian allies invaded the remainder of Czechoslovakia. The area of the modern Czech Republic, then called Bohemia and Moravia, was incorporated into the Third Reich, and a Nazi client state was created in Slovakia.

Despite this violation of the Munich Agreement, Britain and France did nothing, continuing to pursue their policy of appeasement.

Hitler now began negotiations with his arch rivals and political enemies, the Communist Soviets. His foreign minister, Joachim von Ribbentrop, met several times with his Soviet counterpart, Vyacheslav Molotov, and together they agreed the Molotov-Ribbentrop Pact, which was signed by the two nations on August 23 1939. By signing it, they agreed to a policy of non-aggression against the other country, and to a policy of neutrality if the other party was attacked.

However, within the pact, there was also a secret clause, detailing how Eastern Europe would be divided along the basis of German and Soviet spheres. Germany earmarked western Poland and Lithuania while the Soviet Union agreed to receive parts of Finland along with Estonia, Latvia and the remainder of Poland.

A week later, on September 1, Germany acted upon this secret clause, launching its invasion of Poland. This time the governments of France and Britain decided that Hitler had now gone too far. They had a pact which required them to protect Poland if it was attacked. They requested that Germany withdraw, it failed to do so, and so at 11 o'clock on September 3 1939, Neville Chamberlain announced to this country that a state of war existed between Britain and Germany. France, New Zealand, Australia, South Africa and Canada soon followed suit.

Germany enjoyed quick success against the Poles. Though they defended their country well, they were outmanoeuvred and outclassed by the quality of the German armed forces. German forces attacked from Germany herself, their enclave in East Prussia and also from their newly conquered territories in Czechoslovakia, forcing the Poles to spread their forces impossibly thin. In just two weeks most of the Polish army had ceased to exist, though Warsaw and a few other places still held out.

On September 17, anxious to claim their share of Poland, the Soviets invaded Poland from the east, crushing any Polish hopes of regrouping and launching a counter-offensive against the Germans. On September 28 Warsaw surrendered and on October 6 the last Polish field units followed suit.

Despite their decision to declare war, the western allies remained rather complacent about the war. A half-hearted French offensive was launched into Germany in September 1939 but it was almost immediately called off, the allied commanders not wishing to provoke Germany.

Britain's first victory over the Germans came at sea off the coast of South America. There a squadron of British cruisers, the Ajax, Achilles and Exeter, cornered the German pocket-battleship and commerce raider, Admiral Graf Spee. It retreated into Montevideo harbour but was ordered to leave within 72 hours. Believing that defeat was inevitable, Captain Langsdorf scuttled his ship and later committed suicide.

The news was warmly received by the First Lord of the Admiralty, Winston Churchill, and he set about planning his next venture. Germany received much of its iron ore from the port of Narvik, in north Norway. Churchill planned to take the port, which could also then serve as a point for supporting the Finns who were at that time at war with the Soviet Union. After a lot of deliberating, the Norway expedition was eventually agreed on by allied commanders and politicians.

But the expedition was badly organised and the Germans got to Norway first. The Allies' first land campaign against the Germans was a disastrous failure, resulting in the eventual evacuation of the mainly British expeditionary force from the ports of Namsos and Andalsnes on May 2 and May 3, and from Narvik on June 8.

In the House of Commons, the Norway failure prompted a fierce debate which included a speech from David Lloyd George, Prime Minister at the end of the First World War, calling for Neville Chamberlain's resignation. Once the question of his successor was determined, Chamberlain went to the king and offered his resignation. The King accepted and sent for Winston Churchill.

That same day, May 10 1940, the Germans launched an invasion of France, Belgium and the Netherlands. The use of blitzkrieg tactics, close support of fast-moving armoured divisions with aircraft, completely overran the far numerically superior Allied forces. In just four days the Netherlands was forced to surrender, following the fire bombing of Rotterdam.

French and British forces fared little better. They were unable to prevent German panzer regiments from reaching the English Channel on the Somme estuary in just ten days, isolating the British Expeditionary Force in the north of France around the port of Dunkirk.

By May 26, all British forces had been corralled onto the beaches at Dunkirk and the following day the famous evacuation began. By June 4, hundreds of little ships had rescued 338,226 French and British soldiers from France. On June 18, the Prime Minister, Winston Churchill, issued a speech to the House of Commons, in which he stated: “What General Weygand has called the Battle of France is over. I expect that the Battle of Britain is about to begin.”