After the preparations had been finished Sultan Mehmet sent a messenger to the Emperor and invited him to surrender. However, Constantine rejected this request. In April 1453 Sultan Mehmet invested the city with an army of a hundred and twenty thousand men, desolated the environs and confined the inhabitants within their walls. The army was divided in to three, central, left and right. In April 19 the first attack was made. Roller towers were constructed to reach the city walls.

There was a very bloody war going on and the Venetian and Genose navies were helping the Byzantine Empire. Mehmed had realised that unless the Ottoman Navy did not involved in the war, it would very difficult to capture the city. However, the entrances of the Golden Horn(Istanbul Strait) were surrounded with huge chains and it was impossible to enter. As a genius commander Sultan Mehmet had designed a mechanism to slide the ships from the land to the sea. Huge slides were built and they were oiled and the ships were moved downwards, on 22th April, 72 Turkish ships were located on the Golden Horn and began to bombard the city walls.

Because of the long and bloody wars, the Ottoman Army began to lose faith, but, Sultan Mehmet never lost his faith and bravery, he made an oration to his soldiers and declared that on May 29 the fatal attack will be made and Istanbul will be captured. As he told, 29th May the fatal attack was made and a company led by Hassan of Ulubad crossed the ruins in the ditch, gained the breach and mastered the position. The Emperor Constantine fell in defending it. Istanbul has fell.

The siege took 53 days, there were four great attacks of Sultan Mehmet’s army; one in April 19, one in May 6, one in May 12 and the last one in May 29. In the end, 1125 years old Byzantine Empire had came to an end and Istanbul became a Turkish city.