When and how did the Ottoman Turks conquer Constantinople?

The first siege of Constantinople (modern Istanbul) took place in 1494-1402, then Bayezid I was the sultan, and John VII Palaeologus was the emperor of Byzantium. In 1402, the Turks were suddenly defeated at Ankara from Tamerlane and the siege was lifted, the Ottomans began a turmoil, and Byzantium received a respite for almost 50 years and even managed to keep the Princes’ Islands in the Sea of ​​Marmara. Sultan Mehmet began the last war with them in 1452 and in April-May 1453 he gathered a huge army and took Constantinople by storm, where there was a garrison of several thousand people, including Italians, who defended their trade interests. Emperor Constantine XI and Condottiere Giustiniani died, who was able to leave the city by ship, but died on the island of Chios.

The Ottoman army of about 80 thousand people took part in the siege of Constantinople, a garrison of 7-8 thousand was held against them.