Vienna

The First Siege of Vienna in 1529 was an attempt by the Ottoman Empire, led by Suleiman the Magnificent, to capture Vienna, Austria. The siege signaled the Ottoman Empire's high point of territorial expansion in central Europe. Vienna's defences were massive for the time, and the city was able to withstand the siege, marking a turning point in stopping the progress of the Ottoman's domination in Europe. The failure of the siege was a significant event in European history that marked the beginning of the long decline of Ottoman influence in Europe.

The Battle of Vienna took place on 12 September 1683 after Vienna had been besieged by the Ottoman Empire for two months. It was a pivotal battle of the Great Turkish War. Holy Roman Emperor Leopold I led the forces of the Holy Roman Empire, while the Polish relief army was led by King John III Sobieski. This battle marked the beginning of the end of Turkish domination in eastern Europe, as the combined forces succeeded in defeating the Ottomans.

The Congress of Vienna was a conference of the major powers of Europe, including Britain, France, Austria, and Russia, from September 1814 to June 1815. The congress aimed to provide a long-term peace plan for Europe by settling critical issues arising from the French Revolutionary Wars and the Napoleonic Wars. Led by Austrian statesman Klemens von Metternich, it redrew the map of Europe, balancing powers and setting the stage for a century of relative peace in Europe known as the Concert of Europe.

On June 28, 1914, Archduke Franz Ferdinand of Austria, heir presumptive to the Austro-Hungarian throne, was assassinated in Sarajevo by Gavrilo Princip, a Bosnian Serb member of the Black Hand. This assassination is widely regarded as the immediate trigger of World War I, as it led to the Austro-Hungarian Empire issuing an ultimatum to Serbia, which eventually led to the mobilization of Europe’s great powers and the onset of the war.

Anschluss refers to the annexation of Austria into Nazi Germany on 12 March 1938. This event was part of Hitler’s expansionist agenda after coming to power in Germany. Austrian Chancellor Kurt Schuschnigg had tried to maintain Austrian independence, but with growing internal pressures and the threat of invasion by Nazi forces, he resigned, and German troops marched into Austria, facing no resistance. The event marked a critical point in the lead-up to World War II.

Vienna was liberated by Soviet troops on April 13, 1945, during World War II. The city had been under Nazi control since the Anschluss of 1938. The battle for Vienna was part of the Vienna Offensive launched by the Soviet Union, and after intense urban warfare, Soviet forces captured the city from the Nazis, marking a crucial step towards the fall of the Third Reich and the end of World War II in Europe.

The Austrian State Treaty was signed on May 15, 1955, in Vienna, and marked the end of the Allied occupation of Austria following World War II. The treaty re-established Austria as a sovereign state and declared its perpetual neutrality. This was seen as a significant step in Austria regaining its independence and positioning itself as a neutral nation during the Cold War, while also preventing Austrian territory from being a Cold War battleground.

The Vienna International Centre (VIC), also known as UNO City, was officially opened on December 12, 1965. The VIC is an important United Nations office complex located in Vienna, Austria, and serves as one of the four major UN offices worldwide, alongside New York, Geneva, and Nairobi. Here, international organizations focus on the areas of nuclear energy, drug control, crime prevention, industrial development, and world trade.

The construction of the Vienna International Centre was completed on January 1, 1980, providing a vital hub for various international organizations. It stands as one of the four United Nations headquarters and hosts the IAEA, UNODC, and UNIDO. The VIC is integral to the multinational diplomacy efforts and serves as a center for conferences addressing major global issues such as nuclear safety, industrial development, and drug control.

The fall of the Iron Curtain was a series of events leading to the collapse of communist regimes in Central and Eastern Europe in 1989. While the entire event did not occur solely in Vienna, the city played a crucial role due to its location near Eastern Bloc countries and its role as a neutral ground for negotiations and meetings during this period. The fall of the Iron Curtain was symbolized by political reforms and the opening of borders which dramatically changed the geopolitical landscape of Europe.

On January 1, 1995, Austria officially became a member of the European Union. This was a significant event as Austria joined along with Sweden and Finland, marking a substantial enlargement of the EU towards central and northern Europe. Austria's accession was driven by a referendum held in 1994 where a majority of Austrians voted in favor of joining the EU, seeing it as a strategic move to bolster political and economic stability in the post-Cold War era.

On July 14, 2015, the Joint Comprehensive Plan of Action (JCPOA), commonly known as the Iran Nuclear Deal, was signed in Vienna between Iran, the P5+1 (the five permanent members of the United Nations Security Council—China, France, Russia, United Kingdom, United States—plus Germany), and the European Union. The agreement was meant to limit Iran's nuclear activities in return for lifting nuclear-related economic sanctions, marking a milestone in diplomatic negotiations regarding nuclear non-proliferation.