{{Short description|1453 Ottoman conquest of the Byzantine capital}}
{{For|other sieges of the city|List of sieges of Constantinople}}
{{pp-protected|small=yes}}
{{Use dmy dates|date=December 2023}}
{{Infobox military conflict
| part_of = the [[Byzantine–Ottoman wars]]
| image = Siege of Constantinople fresco, Moldovița monastery, Vatra Moldoviței, 2017.jpg
| image_size = 330px
| caption = The Fall of Constantinople on a mural at the [[Moldovița Monastery]], painted in 1537
| date = 6 April – 29 May 1453
({{Age in years, months, weeks and days|month1=4|day1=6|year1=1453|month2=5|day2=29|year2=1453}})
| location = [[Constantinople]], Byzantine Empire (present-day [[Istanbul]], Turkey)
| coordinates = {{Coord|41.030|N|28.935|E|display=inline,title}}
| result = Ottoman victory
| territory = * Constantinople conquered by the Ottomans
* Fall of the [[Byzantine Empire]]
| combatant1 = {{ubl|{{flagicon|Ottoman Empire|1453}} [[Ottoman Empire]]}}
* [[File:Coat of arms of the Serbian Despotate.svg|30x20px]] [[Serbian Despotate]]{{NoteTag|[[Đurađ Branković]], being a vassal of the Ottoman Empire, was asked by Mehmed to send 1,500 soldiers to support him in his campaign against the [[Karamanids|Emirate of Karaman]].{{sfnp|Véber|2024|p=369}} As such, the Serbians believed that they would be fighting against the [[Karamanids]], but they were actually deployed in Constantinople instead. When they found out that the attack was going to be carried out in Constantinople, they wanted to return home, but they were threatened to be killed if they did so.{{sfnp|Véber|2024|p=369}}}}
| combatant2 = {{plainlist}}
*{{flagicon image|Byzantine_imperial_flag,_14th_century.svg}} [[Byzantine Empire under the Palaiologos dynasty|Byzantine Empire]]
*{{flagicon image|Flag of Genoa.svg}} [[Republic of Genoa]]
*{{flagicon image|Flag of Republic of Venice (1659-1675).svg}} [[Republic of Venice]]
* {{flag|Papal States|old}}
* {{flagicon image| Royal Banner of Aragón.svg}} [[Crown of Aragón|Crown of Aragon]]
* {{flagicon image|Bandiera del Regno di Sicilia 4.svg}} [[Kingdom of Sicily]]{{sfnp|Giardinetto|2022}}
* {{flagicon image|Royal flag of France.svg}} [[Kingdom of France]]
* [[File:Byzantine banner, Madrid Skylitzes, fol. 43b.png|25px]] [[Varangian Guard]]{{Cite thesis |last=Wolfe |first=Jacob |title=Imperial nostalgia: The war for the Kievan Rus legacy. |date=2024 |publisher=University of Louisville |url=https://ir.library.louisville.edu/etd/4435 |doi=10.18297/etd/4435 |page=22|url-access=subscription }}
* {{flagicon|Ottoman Empire|1453}} [[Orhan Çelebi]] loyalists
{{endplainlist}}
| commander2 = {{plainlist}}
* '''[[Constantine XI Palaiologos|Constantine XI]]'''{{KIA}}
* [[Loukas Notaras]]{{Executed}}
* [[Theophilos Palaiologos]]{{KIA}}
* [[Demetrios Palaiologos Kantakouzenos|Demetrios
Kantakouzenos]]{{Executed}}
* [[Andronikos Palaiologos Kantakouzenos|Andronikos Kantakouzenos]]{{Executed}}
* [[Giovanni Giustiniani Longo|Giovanni Giustiniani]]{{DOW}}
* [[Gabriele Trevisano]]{{POW}}
* [[Alviso Diedo]]{{WIA}}
* [[Gabriele Orsini del Balzo]]{{KIA}}{{sfnp|Giardinetto|2022}}{{sfnp|Lilie|2005|p=464}}
* [[Isidore of Kiev|Cardinal Isidore]]{{POW}}
* [[Johannes Grant]]{{KIA}}
* [[Orhan Çelebi]]{{Executed}}
{{endplainlist}}
| strength2 = {{ubl|'''Land forces:'''
{{flagicon image|Byzantine_imperial_flag,_14th_century.svg}} Less than 8,000 soldiers in total, including:}}
* 5,000 Byzantine soldiers{{Cite book |last=Kaldellis |first=Anthony |url=https://www.google.com.tr/books/edition/The_New_Roman_Empire/dPjTEQAAQBAJ |title=The New Roman Empire: A History of Byzantium |date=2021 |publisher=Oxford University Press |isbn=978-0-19-754934-6 |pages=6, 119, 910 |language=en}}
* 2,000 Western soldiers{{NoteTag|Western soldiers included, but weren't limited to, [[Italians]] ([[Venetians]], [[Genoa|Genoese]], [[Republic of Ancona|Anconitans]], [[Kingdom of Sicily|Sicilians]] and others), [[French people|French]], [[Spaniards]], [[Germans]] and [[Scottish people|Scots]].}}
* 600 Orhan Çelebi loyalists
* 200 Catalan retinue
* 200 [[Cretan archers]]{{sfnp|Lilie|2005|p=464}}{{sfnp|Nicol|2002|p=57}}
{{ubl|'''Naval forces:'''}}
*26 ships
* 10 [[Byzantine Empire under the Palaiologos dynasty|Byzantine]]
* 8 [[Republic of Venice|Venetian]]
* 5 [[Republic of Genoa|Genoese]]
* 1 [[Crown of Aragon|Catalan]]
* 1 [[Republic of Ancona|Anconitan]]
* 1 [[Provence|Provençal]]
| casualties2 = Heavy
| commander1 = {{plainlist}}
* '''[[Mehmed II]]'''
* [[Çandarlı Halil Pasha the Younger|Halil Pasha]]{{Executed}}
* [[Zagan Pasha]]
* [[Suleiman Baltoghlu]]{{WIA}}
* [[Karaca Pasha]]
* [[Hamza Bey]]
* [[Mahmud Pasha Angelović|Mahmud Pasha]]{{cite web |url=https://islamansiklopedisi.org.tr/mahmud-pasa |title=Mahmud Paşa |access-date=26 June 2023 |archive-date=26 June 2023 |archive-url=https://web.archive.org/web/20230626212325/https://islamansiklopedisi.org.tr/mahmud-pasa |url-status=live}}
* [[Ulubatlı Hasan]]{{KIA}}
* [[Hadım Şehabeddin]]
{{endplainlist}}
| strength1 = {{ubl|'''Land forces:'''
{{flagicon|Ottoman Empire|1453}} 100,000{{sfnp|Runciman|1965|p=76}} soldiers in total,{{NoteTag|Some contemporaneous Western sources gave exaggerated figures ranging from 160,000 to 300,000.}} including:}}
* 75,000 regulars{{Cite book |last=Kaldellis |first=Anthony |url=https://academic.oup.com/book/62441 |title=1453: The Conquest and Tragedy of Constantinople |date=2026 |publisher=Oxford University Press |isbn=978-0-19-782750-5 |edition=1 |page=119 |doi=10.1093/oso/9780197827505.001.0001}}
* 20,000 irregulars{{sfnp|Runciman|1965|p=76}}
* 5,000 [[Janissaries]]
{{plainlist}}