On the third day of the conquest, Mehmed II ordered all looting to stop and issued a proclamation that all Christians who had avoided capture or who had been ransomed could return to their homes without further molestation, although many had no homes to return to, and many more had been taken captive and not ransomed.
Byzantine historian George Sphrantzes, an eyewitness to the fall of Constantinople, described the Sultan's actions:
 On the third day after the fall of our city, the Sultan celebrated his victory with a great, joyful triumph.
He issued a proclamation: the citizens of all ages who had managed to escape detection were to leave their hiding places throughout the city and come out into the open, as they were to remain free and no question would be asked.
He further declared the restoration of houses and property to those who had abandoned our city before the siege.
If they returned home, they would be treated according to their rank and religion, as if nothing had changed.

— George Sphrantzes
The Hagia Sophia was converted into a mosque, but the Greek Orthodox Church was allowed to remain intact and Gennadius Scholarius was appointed Patriarch of Constantinople.
This was once thought to be the origin of the Ottoman millet system; however, it is now considered a myth and no such system existed in the fifteenth century.

The fall of Constantinople shocked many Europeans, who viewed it as a catastrophic event for their civilization.
Many feared other European Christian kingdoms would suffer the same fate as Constantinople.
Two possible responses emerged amongst the humanists and churchmen of that era: Crusade or dialogue.
Pope Pius II strongly advocated for another Crusade, while the German Nicholas of Cusa supported engaging in a dialogue with the Ottomans.

The Morean (Peloponnesian) fortress of Mystras, where Constantine's brothers Thomas and Demetrius ruled, constantly in conflict with each other and knowing that Mehmed would eventually invade them as well, held out until 1460.
Long before the fall of Constantinople, Demetrius had fought for the throne with Thomas, Constantine, and their other brothers John and Theodore.
Thomas escaped to Rome when the Ottomans invaded Morea while Demetrius expected to rule a puppet state, but instead was imprisoned and remained there for the rest of his life.
In Rome, Thomas and his family received some monetary support from the Pope and other Western rulers as Byzantine emperor in exile, until 1503.
In 1461 the independent Byzantine state in Trebizond fell to Mehmed.

Constantine XI had died without producing an heir, and had Constantinople not fallen he likely would have been succeeded by the sons of his deceased elder brother, who were taken into the palace service of Mehmed after the fall of Constantinople.
The oldest boy, renamed to Murad, became a personal favourite of Mehmed and served as Beylerbey (Governor-General) of Rumeli (the Balkans).
The younger son, renamed Mesih Pasha, became Admiral of the Ottoman fleet and Sancak Beg (Governor) of the Province of Gallipoli.
He eventually served twice as Grand Vizier under Mehmed's son, Bayezid II.

With the capture of Constantinople, Mehmed II had acquired the future capital of his kingdom, albeit one in decline due to years of war.
The loss of the city was a crippling blow to Christendom, and it exposed the Christian West to a vigorous and aggressive foe in the East.
The Christian reconquest of Constantinople remained a goal in Western Europe for many years after its fall to the Ottoman Empire.
 Rumours of Constantine XI's survival and subsequent rescue by an angel led many to hope that the city would one day return to Christian hands.
Pope Nicholas V called for an immediate counter-attack in the form of a crusade, however no European powers wished to participate, and the Pope resorted to sending a small fleet of 10 ships to defend the city.
The short lived Crusade immediately came to an end and as Western Europe entered the 16th century, the age of Crusading began to come to an end.

For some time Greek scholars had gone to I
On the third day of the conquest, Mehmed II ordered all looting to stop and issued a proclamation that all Christians who had avoided capture or who had been ransomed could return to their homes without further molestation, although many had no homes to return to, and many more had been taken captive and not ransomed. Byzantine historian George Sphrantzes, an eyewitness to the fall of Constantinople, described the Sultan's actions:
 On the third day after the fall of our city, the Sultan celebrated his victory with a great, joyful triumph. He issued a proclamation: the citizens of all ages who had managed to escape detection were to leave their hiding places throughout the city and come out into the open, as they were to remain free and no question would be asked. He further declared the restoration of houses and property to those who had abandoned our city before the siege. If they returned home, they would be treated according to their rank and religion, as if nothing had changed. 
— George Sphrantzes
The Hagia Sophia was converted into a mosque, but the Greek Orthodox Church was allowed to remain intact and Gennadius Scholarius was appointed Patriarch of Constantinople. This was once thought to be the origin of the Ottoman millet system; however, it is now considered a myth and no such system existed in the fifteenth century.
The fall of Constantinople shocked many Europeans, who viewed it as a catastrophic event for their civilization. Many feared other European Christian kingdoms would suffer the same fate as Constantinople. Two possible responses emerged amongst the humanists and churchmen of that era: Crusade or dialogue. Pope Pius II strongly advocated for another Crusade, while the German Nicholas of Cusa supported engaging in a dialogue with the Ottomans.
The Morean (Peloponnesian) fortress of Mystras, where Constantine's brothers Thomas and Demetrius ruled, constantly in conflict with each other and knowing that Mehmed would eventually invade them as well, held out until 1460. Long before the fall of Constantinople, Demetrius had fought for the throne with Thomas, Constantine, and their other brothers John and Theodore. Thomas escaped to Rome when the Ottomans invaded Morea while Demetrius expected to rule a puppet state, but instead was imprisoned and remained there for the rest of his life. In Rome, Thomas and his family received some monetary support from the Pope and other Western rulers as Byzantine emperor in exile, until 1503. In 1461 the independent Byzantine state in Trebizond fell to Mehmed.
Constantine XI had died without producing an heir, and had Constantinople not fallen he likely would have been succeeded by the sons of his deceased elder brother, who were taken into the palace service of Mehmed after the fall of Constantinople. The oldest boy, renamed to Murad, became a personal favourite of Mehmed and served as Beylerbey (Governor-General) of Rumeli (the Balkans). The younger son, renamed Mesih Pasha, became Admiral of the Ottoman fleet and Sancak Beg (Governor) of the Province of Gallipoli. He eventually served twice as Grand Vizier under Mehmed's son, Bayezid II.
With the capture of Constantinople, Mehmed II had acquired the future capital of his kingdom, albeit one in decline due to years of war. The loss of the city was a crippling blow to Christendom, and it exposed the Christian West to a vigorous and aggressive foe in the East. The Christian reconquest of Constantinople remained a goal in Western Europe for many years after its fall to the Ottoman Empire.  Rumours of Constantine XI's survival and subsequent rescue by an angel led many to hope that the city would one day return to Christian hands. Pope Nicholas V called for an immediate counter-attack in the form of a crusade, however no European powers wished to participate, and the Pope resorted to sending a small fleet of 10 ships to defend the city. The short lived Crusade immediately came to an end and as Western Europe entered the 16th century, the age of Crusading began to come to an end.
For some time Greek scholars had gone to I
Fall of Constantinople