The Fall of Constantinople
Constantinople (Istanbul, as we call the city nowadays) was besieged by Ottoman forces for 53 days before it fell in 1453. The man who finally took the city was Mehmed the Conqueror, who overthrew the last lingering influence of the Roman Empire and turned the city into the seat of the Ottoman Empire.
The fall of Constantinople represents a sea change in the Middle East. It was a huge victory for Islam and a massive loss for Christianity. It would allow for further Ottoman incursions into Europe, particularly the Balkans, and creating the foundation cultural spheres of influence which we understand today.
It was one of the first times that artillery was used in a war, a technological innovation which would be essential for everyone from Napoleon to the German army in both World Wars.
After the sacking, the gradual emigration west of the Christian scholars even helped to inform the Renaissance, spreading knowledge across Europe in the form of ancient texts which were freshly translated. For many people, the fall of the city is considered the end of the Middle Ages and the beginning of a new era.