Beginning at midnight on the 13th August 1961, East German police and army began to close the border with West Berlin. The barbed wire and mesh barrier that was constructed overnight was gradually replaced with a virtually impregnable ring of reinforced concrete that ran 155km around West Berlin.

The border between East and West Germany – sometimes referred to as the inner-German border – had been closed since 1952, although the crossing between East and West Berlin remained open. This easy access proved highly problematic for the Communist government of East Germany, since people comparing the two parts of the city found West Berlin to be much more appealing.

Berlin became a focal point for East Germans who wanted to move to the West, and by 1961 an estimated 20% of the entire population had emigrated. The majority were young, educated, and skilled professionals. This so-called “brain drain” seriously depleted the workforce, and was hugely damaging to the political credibility of East Germany.

The erection of the Berlin Wall was intended to put a stop both of these problems, although it was presented to the East German people as the “Anti-Fascist Protection Rampart”. The East German leader, Walter Ulbricht, had even denied any intention of building a wall just two months earlier despite pressuring USSR Premier Nikita Khrushchev to support him doing just that.

The construction of the Wall turned Berlin overnight from the easiest way to cross between East and West into the most difficult. It cut people off from their jobs, and divided families. The crossing was not opened again for 28 years.

The 16th July 1945 marked the start of the atomic age when the USA detonated the first nuclear bomb under the codename ‘Trinity’. Nicknamed ‘the gadget’ by the people working on it, the plutonium-based weapon was detonated at the Alamogordo Test Range in New Mexico. The explosion was equivalent to about 20 kilotons of TNT, and the blast-wave was felt by civilians up to 160 miles away. To maintain secrecy, a press release was issued shortly after the successful detonation that claimed a large ammunition storage magazine had exploded.

The development of nuclear weapons by the US Army in the Manhattan Project that began in 1942 at Los Alamos Laboratory in New Mexico started due to concerns that Nazi Germany would develop an atomic bomb. By 1944 scientists had designed an implosion-type device and proposed that a test take place. The location was chosen in September, and an on-site laboratory was set up.

President Truman was keen to test the bomb before the Potsdam Conference began on the 18th July, so the 16th was chosen to give time to try again in case it failed. However when the appointed hour came rain was falling, which would have increased radioactive fallout, and so the detonation time was pushed back from 4am to 5.30am. At 5:29am the “the gadget” was exploded on top of a 100-foot steel tower, known as Point Zero. J. Robert Oppenheimer, the director of the Los Alamos Laboratory, later said that after the explosion he recalled a verse from Hindu scripture: ‘Now I am become Death, the destroyer of worlds.’

On the 4th July 1950, Radio Free Europe – founded the previous year to transmit uncensored information to audiences behind the Iron Curtain – completed its first broadcast. Although the station was uncensored in the sense that it shared information that was suppressed within the Communist Bloc, it’s important to remember that it was still a propaganda tool founded and principally funded by the United States government.

The task facing the journalists who worked for RFE was daunting. Since they broadcast to states that suppressed a range of information and news, the gathering of intelligence to provide broadcast material was an enormous challenge. They often relied on risky contact with émigrés and people who had traveled behind the Iron Curtain for eye-witness accounts, and closely monitored print and electronic media from the communist governments. It’s even been suggested that the quality and quantity of information was so comprehensive that the communist governments themselves used Radio Free Europe to gain information about what was happening within their own countries.

However, RFE was still fundamentally a broadcaster that promoted anti-communist ideas and was therefore a significant threat in the countries it targeted. The USSR tasked the KGB with establishing expensive radio jamming facilities to try to block broadcasts, while in 1981 a terrorist group funded by the Romanian regime of Nicolae Ceaușescu detonated a bomb at RFE’s Munich headquarters.

Despite these challenges Radio Free Europe and its partner station Radio Liberty continued broadcasting, and even after the end of the Cold War has continued to broadcast to countries where a free press is not established.

On the 26th June 1963 American President John F. Kennedy declared US support for West Berlin with the phrase, “Ich bin ein Berliner” – I am a Berliner – 22 months after the Soviet-supported DDR, more commonly known as East Germany, built the Berlin Wall.

Berlin had been a focal point for Cold War tensions ever since the Yalta and Potsdam conferences in 1945 divided the city – and the rest of Germany – between the four victorious powers at the end of the Second World War. When the USSR imposed the Berlin Blockade from 1948-49, the Western allies made it clear that they were not willing to back down in their support for West Berlin by airlifting supplies into the city.

Although the airlift secured West Berlin’s survival, it further increased tensions between the USSR and its former allies as East Germans crossed the border in order to defect to the West. This placed an enormous economic strain on the East, which began suffering labour shortages. In response, the government of East Germany erected a barbed wire fence around West Berlin that eventually developed into the imposing Berlin Wall, although the government claimed that it was to keep out spies and agitators rather than stop people from leaving.

It was against this background of heightened tension that Kennedy delivered his rousing speech on the steps of the Rathaus Schöneberg, the seat of the state senate of West Berlin. While the speech effectively recognised East Berlin as part of the Soviet Bloc, it also reaffirmed America’s commitment  to defend West Berlin against Communist expansion.

On June 16th 1958, Hungarian Communist politician Imre Nagy was executed. Arrested after Soviet forces brought the Hungarian Revolution of 1956 to an end, Nagy was found guilty of treason in a secret trial and executed by hanging.

Nagy had been sacked from his position as Chairman of the Council of Ministers in April 1955 due to his independent attitude that favoured a “New Course” in Socialism. Although his moderate reforms were met with hostility from the USSR, they garnered significant support within Hungary where opposition to the hard-line government of Mátyás Rákosi had grown since the death of Stalin in 1953. Nagy’s popular support led to him being appointed Prime Minister on October 24th 1956, the day after the Revolution began.

After a week of violence, Nagy recognised the crowd’s desire for political change. Despite being an ardent Marxist he began moves towards introducing a multiparty political system and, on November 1st, announced Hungary’s withdrawal from the Warsaw Pact and its status as a neutral country. This proved too much for Khrushchev in the USSR, who moved his troops into Budapest and seized control of most of the city by the 8th November. Nagy took refuge in the Yugoslavian embassy, but was arrested when he was given false promises of safe passage to leave Hungary on the 22nd November.  He, and other leading members of the deposed government, were imprisoned in Romania until 1958 when they were returned to Hungary for trial.

News of Nagy’s trial and execution were only made public after the sentence had been carried out.

On the 25th May 1961, American President John F. Kennedy made the announcement to a joint session of Congress that he had set his sights on a manned moon landing before the end of the decade.

To many people, including some personnel at NASA, Kennedy’s address seemed ridiculous. The USA had only sent its first man into space 20 days earlier and, although Alan Shepard’s spaceflight aboard Freedom 7 was a huge success, the USSR’s Yuri Gagarin had already become the first man in space three weeks before that. Taking on the USSR at a technological game that they were already leading appeared reckless.

An underlying issue was that, as part of his election campaign, Kennedy had promised to outperform the Soviet Union in the fields of space exploration and missile defence. In his famed television debate with Richard Nixon, Kennedy had mocked the fact that Nixon was proud of the USA being ahead of the USSR in terms of colour television while trailing in terms of rocket thrust. Gagarin’s flight had proved to the world that the USSR was currently ‘winning’ the Space Race, and so put pressure on Kennedy to increase spending on the Apollo space program.  Having received a memo from Vice-President Lyndon B. Johnson in which he reported that the USA was unlikely to ever outperform the USSR under the current spending arrangements, Kennedy launched the largest peacetime financial commitment ever made.

The $24 billion dollars did work, however, and Apollo 11 achieved Kennedy’s goal by landing on the moon on 20th July 1969.

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.

The Battle of Berlin ended after German General Helmuth Weidling surrendered to Soviet General Vasily Chuikov.

Determined to capture Berlin before the Western Allies, Stalin’s generals began their assault on the defensive line of the Oder and Neisse rivers on the morning of 16 April. 2 million German civilians and no more than 200,000 German soldiers were in and around Berlin when the USSR broke through the defences having suffered casualties in the tens of thousands.

Travelling at up to 30-40km a day, the first Red Army troops reached Berlin in time for Hitler’s 56th birthday on 20 April. Artillery began bombarding the city and didn’t cease until the surrender almost two weeks later. Meanwhile other Soviet units encircled the city leading to Hitler, who was based in the Führerbunker, angrily declaring that the war was lost. Nevertheless he appointed General Weidling to command the Berlin Defence Area with a force of 45,000 soldiers supported by police officers, members of the Hitler Youth, and the Volkssturm militia.

By 30 April Soviet troops had reached the Reichstag and, late that evening, successfully placed a flag on top that was removed the following morning by German defenders. The building was finally taken over on 2 May and a new flag was raised, of which an iconic photograph was taken. General Weidling and his staff surrendered the same morning having failed to negotiate a conditional surrender.

Following the surrender the Soviets sought to restore essential services and provide food to the German survivors. However, some troops who reached the city lacked the discipline of the first echelon and committed shocking crimes against Berliners including rape, pillage and murder.

On the 5th March 1946, Winston Churchill described the post-war division of Europe as an “iron curtain” in his “Sinews of Peace” address at Westminster College in Fulton, Missouri. Often interpreted as a key event in the origin of the Cold War, Churchill’s speech played a significant role in changing Western perceptions of their former Soviet ally.

Churchill, as the British Prime Minister, had led Britain to victory in the Second World War but in the General Election of July 1945 suffered a landslide defeat to Clement Attlee’s Labour Party. Despite now being in opposition, he continued to be highly respected abroad and visited the United States in 1946. During this trip he was invited by Westminster College in the 7,000-person town of Fulton to deliver a speech to an audience of 40,000 people.

Churchill was introduced at Fulton by President Harry Truman, and opened his speech by complimenting the United States as standing “at the pinnacle of world power.” As the speech progressed, he became increasingly critical of the Soviet Union’s policies in Eastern Europe. Churchill was not the first to use the term “iron curtain” as a metaphor for a strong divide since versions of its had been in use for many centuries, and nor was the “Sinews of Peace” speech the first time that he himself had used the term. However, his use of the term in a speech with such a large audience thrust it into wider circulation and associated it directly with the post-war situation.

Stalin accused Churchill of warmongering, and defended the USSR’s relationship with eastern Europe as a necessary barrier to future attacks.

The German Empire established its first air force, the Fliegertruppe, in 1910 which saw extensive action in the First World War. Following Germany’s defeat and the signing of the Treaty of Versailles, Germany was banned from possessing an air force and the Fliegertruppe was dissolved.

Despite the ban, the German military established a secret flight school at Lipetsk in the Soviet Union that began training fighter pilots and ground crew from 1926. This meant that there were already up to 120 trained pilots by the time Hitler came to power in January 1933. Senior Nazi, and former First World War pilot Hermann Goering, was named Reich Commissioner of Aviation.

On 15 May 1933 the Reich Ministry of Aviation took control of all military flying operations. Although often considered by many to be the ‘birth’ of the Luftwaffe the development of military aircraft continued in secret. Having formally approved its position as a third military service alongside the army and navy on 26 February 1935, Hitler and Goering began to reveal the Luftwaffe.

Germany’s expansion of its air force was protested by both France and Britain, the latter of which had begun to strengthen the Royal Air Force in March. However, neither country nor the League of Nations attempted to sanction this blatant defiance of the Treaty of Versailles. Consequently the Luftwaffe continued to grow, and the following year the Condor Legion saw action for the first time as part of the Nationalist forces in the Spanish Civil War. As a result, up to 20,000 members of the Luftwaffe gained valuable combat experience.