The Battle of Monte Cassino began when Allied forces launched the first of four attacks against the Gustav Line in Italy.

The Gustav Line, which together with the Bernhardt and Hitler lines formed a series of defences known as the Winter Line, had been established by the Germans and Italians to defend Rome from a northern advance by the Allies. The Allied forces had secured a foothold in Italy in Operation Avalanche the previous September, having first captured Sicily.

By early January 1944 the Allies had advanced a long way north, but their progress had been stopped by poor weather that forced them to approach Rome along Highway 6 that ran from Naples through the Liri valley. The southern entrance to the valley was dominated by the town of Cassino and overlooked by the Benedictine abbey of Monte Cassino.

Although the German army did not position defensive units in the abbey itself, the natural topography gave them a notable advantage over the Allies. Combined with minefields that had been laid in advance, the strong German position withstood the first assault that lasted for two and a half weeks and involved troops under British, American and French command attacking the position from three sides.

German forces finally withdrew on 17 May, and the following morning soldiers from the Polish 12th Podolian Cavalry Regiment raised a Polish flag over the ruins. The four assaults that made up the Battle of Monte Cassino had led to 55,000 Allied casualities and destroyed the ancient abbey. The treasures it contained had been evacuated to Rome in November 1943.

In November 1923 Hitler had led an attempted coup against the Weimar Government by trying to seize power in the Bavarian city of Munich. The putsch failed and Hitler was found guilty of treason in the subsequent trial. Sentenced to five years imprisonment, he was sent to the Festungshaft prison in the Bavarian town of Landsberg am Lech.

Hitler’s ‘fortress confinement’ provided him with a reasonably comfortable cell in comparison to conventional facilities, and meant that he was able to receive mail and have regular visitors. The discovery in 2010 of more than 500 documents relating the Hitler’s imprisonment show that more than 30 people were able to visit him on his birthday on 20 April 1924, just 19 days into his sentence.

Imprisonment provided Hitler with the opportunity to dictate his autobiography, Mein Kampf, to his deputy Rudolf Hess. It was in this book that Hitler laid out his blueprint for the future of Germany. Although it gained only modest success when it was first published, Winston Churchill later claimed that if world leaders had read it they could have better anticipated the scale of Nazi domestic and foreign policy.

In a memorandum dated 18 September 1924, the Landsberg warden Otto Leybold described Hitler as “sensible, modest, humble and polite to everyone – especially the officers of the facility”. He was released on 20 December 1924 after serving on nine months of his five-year sentence and soon set about rebuilding the Nazi Party which had been banned in Bavaria as a result of the Beer Hall Putsch. The ban was lifted less than two months after Hitler’s release.

On the 25th November 1936, Nazi Germany and the Empire of Japan signed the Anti-Comintern Pact. Although directed against the Communist International, the international organisation that sought to create a worldwide communist republic, the treaty was in reality specifically against the Soviet Union.

The idea for an anti-Communist alliance had first been suggested in late 1935, as Hitler and Mussolini sought to present themselves as upholding traditional values in the face of Soviet Communism. However, the plan stagnated while the German foreign ministry weighed up the pros and cons of an alliance with the arch-enemy of their traditional Chinese ally.

By summer 1936 the military were an increasingly dominant force in Japan’s government. Meanwhile Europe was beginning to fear the implications of the Franco-Soviet Alliance that went into effect at the end of March. As a result Hitler pushed ahead with the Pact in the hope of securing an Anglo-German alliance as a result.

The Pact didn’t result in Hitler’s desired alliance with Britain, but did later expand to include Italy. Mussolini’s decision to join with Germany and Japan on the 6th November 1937, two years after the collapse of the Stresa Front with France and Britain, led to the formation of what was to become known as the Axis Alliance.

The Anti-Comintern Pact specifically stated that the signatories would not make any political treaties with the Soviet Union. However, on the 23rd August 1939, Germany signed the Nazi-Soviet Pact, also known as the Molotov-Ribbentrop Pact. This caused a rift with Japan, but the relationship began to heal following the later Tripartite Pact in September 1940.

Einstein, who was Jewish, was undertaking a visiting professorship at the California Institute of Technology in Pasadena when Adolf Hitler was appointed Chancellor on 30 January 1933. With the Nazis expanding their power in Germany, Einstein chose not to go home when he returned to Europe in March. When his ship docked at the Belgian port of Antwerp on 28 March he renounced his German citizenship by handing in his passport at the German Consulate.

While the Nazis seized Einstein’s cottage and converted it to a Hitler Youth camp, the government barred Jews from teaching at universities and the German Student Union burned his books. With a bounty on his head, Einstein stayed in Belgium for a few months before moving to Britain where he was guarded by his friend, naval officer Commander Oliver Locker-Lampson.

While a refugee in Britain, Einstein lobbied foreign governments and universities to find employment for former German Jewish scientists. Many places were found around Europe, with over 1,000 German Jewish scientists being placed in Turkish universities alone, but Einstein himself was refused British citizenship and instead accepted an offer from the Princeton Institute for Advanced Study in New Jersey. He departed England on 17 October 1933.

Although Einstein initially intended to only stay in the United States for a short time, in 1935 he chose to seek American citizenship, which he gained in 1940. By this time he had warned President Roosevelt about the danger of Hitler developing nuclear weapons, and encouraged the United States to begin its own research.

Boris III became Tsar of Bulgaria at the end of the First World War, just four days after his father, Ferdinand I, signed the Armistice of Thessalonica with the Allied Powers. In order to save the monarchy he handed power to his eldest son, who had gained great respect from both Bulgarian and German troops during the First World War.

The new Tsar found himself leading a country that faced enormous economic and political problems as a result of the war and the subsequent Treaty of Neuilly that was signed in November 1919. Bulgaria was forced to hand territory to both Greece and the newly-formed Yugoslavia, resulting in approximately 300,000 Bulgarians finding themselves in new countries. The army was also reduced and the country was forced to pay reparations.

The first decade of Boris’ reign saw tensions between the monarchy and the powerful forces of the Agrarian Union and the Communist Party. By the end of 1935 he had begun to secure his hold on power and establish the ‘King’s Government’ in which he personally dominated the political system.

The outbreak of the Second World War was followed a year later by Bulgaria allying itself with the Axis powers in an attempt to win back territories lost at the end of the First World War. However, Boris refused to lend unconditional military support to Germany and infuriated Hitler with his refusal to declare war on the USSR. In early 1943 Boris angered Hitler again by refusing to deport Bulgarian Jews. He insisted that they should stay in Bulgaria where they were needed for labouring tasks, and saved approximately 50,000 people. Boris died of apparent heart failure later that year, on 28 August.

On September 12th 1919, Adolf Hitler officially joined the German Workers’ Party (DAP). At the time no membership cards were issued but, when they made available in January 1920, Hitler was given membership number 55 although he later claimed in Mein Kampf to have been the seventh. Hitler was actually the seventh executive member of the Party’s central committee. His membership card actually identified him as number 555 since the party began its numbering at 500 in order to make it appear to have more members than it really did.

At the time Hitler was working as an army intelligence officer who had been tasked with infiltrating the German Workers’ Party. However, he was attracted to the angry rhetoric of the founder – Anton Drexler – and during a party meeting in the first floor restaurant of the Sterneckerbräu beer hall in Munich on the 12th September put forward a passionate argument denouncing the views of another speaker. In Mein Kampf Hitler describes Drexler as being impressed by his oratorical skills, which resulted in him being invited to join the party.

Despite members of the army not being permitted to have membership of a political party, Hitler was given special permission to join the DAP. However, before long his role in the party began to eclipse his role in the military and he was discharged from the army on the 31st March 1920 after which he began working full-time for the renamed National Socialist German Workers Party.

The Sterneckerbräu building still exists in Munich, although the beer hall has gone and it is now used for residential and commercial purposes.

The Nazi German Luftwaffe launched the first of 57 consecutive days and nights of bombing raids on London in what became known as the Blitz.

The Luftwaffe had been attacking British targets in the Battle of Britain since June 1940. This was an attempt to achieve air superiority over the RAF to enable a land invasion by the Nazis or force the British government to sue for peace.

Having failed to defeat the RAF in the Battle of Britain, Hitler and Göring instead ordered a policy designed to crush civilian morale. The first raid of the Blitz took place on 7 September in which over 337 tons of bombs were dropped on London, and 448 civilians were killed. The earlier decision by Hugh Dowding, Air Officer Commanding Fighter Command, to focus on day fighter defences meant that Britain was woefully unprepared for German bomber attacks at night when they became the official policy on 7 October.

The Luftwaffe used technology known as beam navigation to locate their target, in which the crews had to detect converging radio signals from two or more ground stations. Britain countered this by transmitting false navigation signals that were designed to send the incoming crews off course. They also created a number of dummy targets such as diversionary airfields and industrial targets that used lighting effects to simulate factories and transport.

By the end of the Blitz on 11 May 1941, approximately 41,000 tons of bombs had been dropped by the Luftwaffe and more than 40,000 civilians had been killed. Yet, despite the psychological pressures of the situation in which class divisions and anti-Semitism often surfaced, British society continued to function, morale remained high and British industrial production actually rose.

On the 2nd August 1934, the 86 year old German Reichspräsident Paul von Hindenburg died of lung cancer and Adolf Hitler became both the Führer and Reich Chancellor of the German People. It effectively merged the offices of both the President and Chancellor into one role, and therefore completed what the Nazis referred to as Gleichschaltung (or “Co-ordination”) by establishing Hitler as both Germany’s head of state and head of government.

Interfering with the post of President was illegal under the terms of the 1933 Enabling Act, and although Hitler merging the two positions removed any political checks and balances of his personal domination of Germany, a plebiscite held 17 days later on the 19th August saw an enormous 90% of people approving of the change.

Hitler’s assumption of the role of Führer also allowed the Nazi Party to more actively pursue its promotion of the ideology of Führerprinzip. This stated that Hitler possessed absolute control over the German government. Supported by a propaganda machine that relentlessly pushed the slogan Ein Volk, ein Reich, ein Führer – which translates as “One People, One Empire, One Leader” – the Führerprinzip also confirmed the Nazi Party’s complete control over every element of German society. This ranged from local government to factories and even to the management and control schools, although in terms of government it sometimes meant that officials were reluctant to make decisions without Hitler’s personal input or approval. It was also used by Nazi war criminals at the Nuremberg Trials to argue that they were not guilty since they were only following orders.

The Vichy government was established in France after the National Assembly approved a new French Constitutional Law that granted full powers to Marshal Pétain.

France declared war against Germany on 3 September, two days after the Nazi invasion of Poland. Despite being at war, however, the two countries only experienced minor skirmishes in early September.

This period of little military action, which became known as the Phoney War, was followed 8 months later by a full-scale German invasion of France that began on 10 May. The French were overwhelmed by the Nazi war machine, and were soon forced to decide whether to continue to fight while the government relocated to North Africa, or remain in France and seek an armistice.

Eventually the Cabinet agreed to seek an armistice, which was signed on 22 June in Compiègne Forest. This had been the location for the November 1918 armistice that Germany had signed to end the Great War, and was specifically chosen by Hitler as a form of revenge. The railway carriage in which the 1918 ceasefire had been agreed was even brought from a museum to host the discussions.

The French decision to sign an armistice led to the resignation of Prime Minister Paul Reynaud, who was replaced by First World War hero Marshal Philippe Pétain. Two-fifths of France had been designated ‘unoccupied’ under the terms of the armistice, and its administrative centre lay in the city of Vichy. However, the government nominally ruled the German-occupied areas as well.

The French State officially collaborated with Nazi Germany from 30 October, when Pétain announced the policy in a radio broadcast. The new Provisional Government of the French Republic was established on 3 June 1944 following the Allied liberation.

On the afternoon of 26th April 1937, the Basque town of Guernica experienced what is seen by many as the first large-scale modern air raid against a civilian population.

By the Spring of 1937, Guernica was just 30km away from the front line fighting of the Spanish Civil War, and lay within the focal area for the Nationalist army’s advance on the city of Bilbao.  The town was also a Republican communication centre, and was the location of a weapons factory.  Documents released in the 1970s show that the attack was part of a larger Nationalist strategy in the north, in which roads and bridges would be destroyed in order to upset Republican troop movements.

However, as historian César Vidal Manzanares notes, the level of destruction was disproportionate to the town’s strategic value.  At first, five waves of bombers attacked Guernica over a period of 90 minutes.  Further waves came in the early evening, along with a number of fighter planes that strafed the roads leading out of the devastated town, increasing the civilian death toll as people tried to escape the burning ruins.

The number of civilian casualties from the attack has never been fully determined.  However, figures in excess of a thousand that were cited until the 1980s are now known to have been exaggerated.  Historians now accept that between 170 and 300 civilians were killed in the bombing, although it’s likely that many more died from their injuries.