On the 3rd September 1939, the Second World War officially began when France and the United Kingdom – together with Australia and New Zealand – declared war on Germany. Nazi forces had invaded Poland two days earlier, claiming to be acting in self-defence. Although both France and Britain had each signed Pacts with Poland regarding mutual assistance in case of invasion, no significant military action was taken for eight months against Germany. As a result, this period became known as the Phoney War.

However, to call the war ‘phoney’ ignores some key elements of this period. The French, for example, launched an attack across the German border known as the Saar Offensive but the troops were pulled back to their defensive Maginot Line on the 17th October after it became clear that a full-scale assault would not be successful.

Further action took place at sea, where both the British and French navies both began a blockade of Germany’s ports the day after the declaration of war. The previous evening the British passenger ship SS Athenia was hit by torpedoes fired from a Nazi U-boat off the coast of the Hebrides. 128 civilian passengers and crew were killed as a result of the attack, and it is seen by some as marking the start of the Battle of the Atlantic.

British Prime Minister Neville Chamberlain resigned and was replaced by Winston Churchill, on Chamberlain’s own suggestion, on the 10th May 1940. This coincided to the day with Germany’s invasion of the Low Countries using the tactic of blitzkrieg and effectively marked the end of the Phoney War.

On the 1st September 1939, German forces invaded Poland in a move that was to trigger the Second World War. Germany had already removed the threat that the USSR might respond aggressively by signing the Nazi-Soviet Pact a week earlier. Furthermore, the Nazis manufactured a situation in Poland to claim that their military response was an acting of self-defence.

During the night of the 31st August, Nazi SS troops dressed in Polish uniforms and staged an attack on the Gleiwitz radio tower in Upper Silesia. This ‘false flag’ operation was part of a wider series of staged attacks by Germans and German property called Operation Himmler that was designed to make it appear that Poland was exercising aggression against Germany.

Just hours after the Gleiwitz incident, at 4.45am on the 1st September, the first of approximately 1.5million German troops launched their attack on Poland. The effective encirclement of Polish forces by launching the coordinated attack at the same time from the north, south and west. The attack from the south came across the border with Slovakia, which had declared its independence in March under pressure from Hitler.

Known as the Battle of the Border, the three-pronged ground attack was supported by air raids that targeted Polish cities. It took just 5 days for troops on the ground to force the Polish army to retreat to their secondary defensive lines. The USSR joined launched its own invasion from east on the 17th September, and this crushed Polish hopes of victory.

The Polish government refused to surrender to Germany and instead evacuated the country and regrouped in Allied countries.

On 23rd August 1939, Vyacheslav Molotov and Joachim von Ribbentrop – the Soviet foreign minister and the German foreign minister – signed the Treaty of Non-aggression between Germany and the Union of Soviet Socialist Republics, otherwise known as the Nazi-Soviet Pact. Outwardly it was a guarantee that neither side would fight against the other in war, but a ‘secret protocol’ also outlined how Eastern Europe would be divided between the two countries. This agreement cleared the way for the Nazi invasion of Poland just nine days later.

Stalin’s Communist USSR distrusted Hitler’s Nazi Germany, knowing that ultimately Hitler intended to invade and annex Russia. Similarly, Britain distrusted Stalin due a fear of Communism. Although talks took place between Britain and Russia in early August 1939 regarding a possible alliance against Hitler, they were never taken seriously by the British government who sent their representative by a slow boat and gave him no authority to actually make any decisions.

Frustrated, Stalin’s government received Ribbentrop later that month. He proposed the Nazi-Soviet agreement which, in the face of continued British reluctance to form an alliance, was accepted. The Soviet government almost certainly knew that Hitler would break the non-aggression pact at some point and would invade Russia, but at least the pact delayed that and gave time to prepare.

The Nazi-Soviet Pact was broken less than two years after it was signed, when Nazi forces invaded the Soviet Union in Operation Barbarossa on the 22nd June 1941. All the territory gained by Russia under terms of the ‘secret protocol’ was lost in just a matter of weeks.

At around 11pm on the 20th August 1968, troops from the USSR, Bulgaria, Poland and Hungary entered Czechoslovakia in an invasion that brought the Prague Spring to an end. The invasion, known as Operation Danube, led to almost half a million soldiers crossing the border to bring Alexander Dubček’s reforms to an end.

The Prague Spring began in early January, shortly after Dubček became the leader of Czechoslovakia. Keen to push forward with de-Stalinisation within the country, he granted greater freedom to the press and introduced a programme of ‘socialism with a human face’ by which he intended to decentralise parts the economy and introduce some limited democratic reforms.

This new openness saw open criticisms of the Czechoslovakian government begin to appear in the press, which concerned the other Warsaw Pact countries. János Kádár, the leader of Hungary who came to power after the fall of Imre Nagy in 1956, even warned that the situation in Czechoslovakia seemed “similar to the prologue of the Hungarian counterrevolution”.

Concerned that Dubček’s reforms might spread to other Eastern Bloc countries and threaten the USSR’s security, the Soviet leader Brezhnev chose to open negotiations with the Czechoslovakian leadership that lasted into August. The talks ended in compromise, but Brezhnev continued to be unhappy with the situation and began to prepare military intervention.

Overwhelmed by the military invasion, Dubček asked his people not to resist. 72 Czech and Slovak soldiers and 108 civilians were killed, with a further 500 civilians injured. It later emerged that members of the Czechoslovakian government had asked for Soviet assistance against Dubček’s reforms.

On the 14th August 1980, workers at the Lenin Shipyard in the Polish city of Gdańsk led by electrician Lech Wałęsa began a strike that led to the formation of the Solidarity labour movement. A decade of economic and political crises preceded the 1980 strike, but the Gdańsk strike spread throughout Poland and galvanised various other strike committees to join together for a common goal.

The trigger for the strike was the firing of a popular worker at the shipyard, a female crane operator and activist called Anna Walentynowicz. Just 5 months before her planned retirement, she was sacked for being a member of an illegal trade union. This move proved highly unpopular with the shipyard workforce, who demanded that she be reinstated.

Just a week after beginning the strike a governmental commission began negotiations with the strikers and, on the 30th August, they and representatives of the Gdańsk workers signed an agreement in which many of the strikers’ demands were met. The fact that political change, including the resignation of the Polish Communist Party’s General Secretary, had come from the workers’ action emboldened the people of Poland and fuelled the formation of the national labour union Solidarity.

Within two years up to 80% of the entire Polish workforce had joined Solidarity or one of its suborganisations, and they continued to use strikes to achieve political change. In March 1981, the crippling effects of 12 million people going on a four-hour warning strike demonstrated that the Communist Party was no longer the most powerful force in the country.

The USSR and seven other European countries signed the Treaty of Friendship, Cooperation, and Mutual Assistance better known as the Warsaw Pact.

The Warsaw Pact was established shortly after West Germany was admitted to NATO. The USSR was concerned by the remilitarisation of West Germany, something it had tried to avoid when it proposed a new European Security Treaty that failed to gain support from the Western powers in November 1954.

Just five days after West Germany joined NATO representatives of the Soviet Union, Albania, Poland, Romania, Hungary, East Germany, Czechoslovakia, and Bulgaria met in Warsaw where they signed the treaty. While the agreement established a system of collective security between the member states it also set up a unified military command under the leadership of the Soviet Union.

The Pact permitted Soviet troops to be garrisoned on satellite territory, consequently strengthening Soviet control over the Eastern Bloc and acting as a military counterpart to Comecon, the socialist economic organisation that had been established in 1949.

The presence of Soviet troops was a contributing factor to the 1956 uprisings in both Hungary and Poland. Both these countries did, however, take part in the Warsaw Pact invasion of Czechoslovakia in 1968 that ended the Prague Spring. Only Romania and Albania refused to join the invasion, the latter subsequently withdrawing completely from the pact.

The Warsaw Pact was formally declared “nonexistent” on 1 July 1991, although in practice it had been in decline for two years as a result of the overthrow of communist governments in the member states that had begun in 1989.

On the 20th January 1942, a number of senior Nazis met at the Wannsee Conference where they discussed what was referred to as the Final Solution to the Jewish Question. SS-Obergruppenführer Reinhard Heydrich called the meeting, in which he outlined the deportation of European Jews to extermination camps in Poland where they would be systematically murdered.

Six months earlier, on the 31st July 1941, Hermann Goering had ordered Heydrich as his second-in-command to submit plans “for the implementation of the projected final solution of the Jewish question”. Heydrich was a trusted member of the Nazi elite, and had been referred to by Hitler as “the man with the iron heart”. He had already helped to organise Kristallnacht, established Jewish ghettos in Nazi-controlled territories, and command the Einsatzgruppen that were responsible for millions of Jewish deaths prior to his planning of the Final Solution.

Heydrich originally planned for the Wannsee Conference to take place on 9th December 1941, but it was postponed due to the USSR’s counter-offensive in the Battle of Moscow and the entry of the USA into the war. Fifteen representatives from a variety of government ministries attended the delayed meeting on the 20th January instead.

By this time hundreds of thousands of Jews had already been killed in the east, and the planning and construction of extermination camps had already begun. The meeting was, therefore, more to ensure coordination between the various government agencies in implementing the deportations.

Minutes from the meeting survive as what is known as the Wannsee Protocol, although the language was edited so that mass extermination was never explicitly recorded.

Napoleon’s Grande Armée began its failed invasion of Russia when it crossed the Neman River in what Russians refer to as the Patriotic War of 1812.

Russia had upset Napoleon by withdrawing from the Continental System, a French-led embargo against trade with Britain, in 1810. Meanwhile the Russian Tsar, Alexander I, was concerned by the formation of the Grand Duchy of Warsaw to the south. Napoleon consequently led his army across the Neman River in an attempt to secure Poland from the threat of a Russian invasion, and to force the Tsar to once again cease trading with Britain.

Up to 650,000 French soldiers invaded Russian Poland on 24 June for what Napoleon hoped would be a quick victory. The Grande Armée made significant progress into the Russian interior, forcing the Tsar’s vastly outnumbered forces back into Lithuania, but erratic weather conditions made the advance difficult. Supply wagons struggled on muddy tracks caused by thunderstorms while the troops were affected by sunstroke and disease in the hot and humid swamp-like conditions.

The retreating Russians also adopted scorched-earth tactics that destroyed farmland and villages, making it increasingly difficult for Napoleon to feed his army. Despite the problems this caused, the French successfully advanced for almost three months before reaching Moscow. The city had been evacuated, and Napoleon’s hopes of agreeing a peace treaty with Alexander were not realised.

Realising that his troops could not survive the winter, Napoleon led his army out of Moscow at the end of October. However, his numbers were seriously depleted and by December an estimated 380,000 men had died while another 100,000 had been captured.

On the 4th February 1945 the Yalta Conference began. Attended by the “Big Three” Allied leaders, the conference saw United States President Franklin D. Roosevelt, British Prime Minister Winston Churchill and Soviet Premier Joseph Stalin meet to discuss the government of post-war Europe.

The three leaders had previously met at the Tehran Conference in 1943 where they set out a unified military strategy, but at Yalta the focus was exclusively on the end of the war and its aftermath. It was clear that the war in Europe was in its final stages, so they agreed to demand Germany’s unconditional surrender after which the country – and Berlin – would be split into four zones of occupation. Germany was to undergo a process of demilitarization and denazification, and Nazi war criminals were to be hunted down and brought to justice.

Furthermore, the three allies considered the fate of Eastern European countries that had been under Nazi occupation. Poland was the focus of much of the discussion, but the agreement reached was intended to apply to every country. The Protocol of Proceedings stated that the allies would assist the liberated countries to form “interim governmental authorities broadly representative of all democratic elements in the population…and the earliest possible establishment through free elections of governments responsive to the will of the people.”

The terms of the agreement, when they were made public, were met with harsh criticism in Britain and the United States. Some of these criticisms came to be justified when, at the end of the war, the Soviet Union installed communist governments throughout Eastern Europe.

On the 27th January 1945, Soviet soldiers from the 322nd Rifle Division liberated the Auschwitz-Birkenau concentration camp near the Polish city of Oświęcim. They met some resistance from the remaining Nazi troops in the city, but by 3pm had captured the Main Camp and Auschwitz II-Birkenau.

By the end of 1944, the Soviet Union was making significant gains against the Nazis on the Eastern Front. As a result SS chief Heinrich Himmler ordered the end of gassings across the Reich, and the systematic destruction of written records. Approximately 65,000 prisoners were evacuated deeper into the Reich between August 1944 and January 1945 but tens of thousands of prisoners still remained in Auschwitz. Therefore, on the 17th January, at least another 58,000 inmates were sent on a death march under armed guard; of those who departed around 20,000 made it to the Bergen-Belsen concentration camp in Germany.

More than 7,000 prisoners were left behind in the camp because they were deemed too weak or sick to complete the march. Meanwhile, the Nazis continued to destroy evidence of the crimes committed in the camps by blowing up or burning many remaining buildings including the crematoria. Remaining SS troops were ordered to kill the remaining inmates, murdering over 600 of them before the Soviet forces arrived. However, due to the quick progress of the Red Army some buildings – as well as thousands of inmates – survived.

After the liberation, hospital facilities were established at the camp to provide medical treatment for the survivors. On the 2nd July 1947, the Polish parliament passed an act that turned the camp in to a museum.