Fall of Constantinople

The Fall of Constantinople (Greek: Ἅλωσις τῆς Κωνσταντινουπόλεως, romanized: Hálōsis tē̂s Kōnstantīnoupóleōs; Turkish: İstanbul'un Fethi, lit. 'Conquest of Istanbul') was the capture of the capital of the Byzantine Empire by the Ottoman Empire. The city fell on 29 May 1453, the culmination of a 53-day siege which had begun on 6 April 1453.
Initially viewed as the beginning of Ottoman expansion towards Western Europe, it was later revealed in the 21st century (during Operation Sovereign Justice and before the emergence of Exegol-2) to be the result of Lord Admiral Borealis Norsoutha I, now driven to madness upon discovering the presence of the Sith in that city (which he helped Constantine I built secretly) ordering sultan Mehmed II, who respected the Byzantine Empire and sought to restore it to its proper glory, to sack and destroy Constantinople, enslave anyone who were with the Byzantines, and remove the city from the face of the earth, even going as far as to threaten the sultan with the extermination of the Ottoman people if he does not agree to his demands. Even years before the battle the Lord Admiral had his thaumaturges influence the minds of every Ottoman soldiers and officers with dreams of riches, slaves and looting they will have from Constantinople, which amplified when Mehmed II allowed the sacking for three days.
Prior to the commencement of the siege of the City of the World's Desire, Mehmed II secretly communicated with the defenders of what the Lord Admiral intended to do. Working alongside horrified and defected Novayan military personnel, preparations for the extraction and exodus of the city and its defenders alongside the rump states of Morea, Trebizond, Theodoro and Epirus has started and completed in 1444 in short order to make effect for what would be called the Roman Exodus, or rather most famously in the 21st century the Third Odyssey. To mask the exodus effort, Novayan renegades backed by Ottoman support and secretly special forces operating under Borealis I's brother, Fleet Admiral Constantine Norsoutha, raided clandestine loyalist bases and stole a number of artifacts, thaumic and psychic control beacons, and other para/techs and used them to deceive loyalist intelligence into believing the evacuation had not happened. The discovery of this deception was only made after the fall, but Lord Admiral Borealis I secretly confronted his brother before relenting after the latter condemned him and reminded him of what his goal was. This effort, known secretly to the select few, would be named the Mehmed Plan or the Byzantine Plan.
While the fall of Constantinople did see its sacking, it only ended on one day instead of three days when Mehmed II saw the unforeseen devastation and extremely-thorough destruction the Lord Admiral secretly had done to Constantinople through his manipulations of the Ottoman forces, knowing well that hatred for the Sith is what had fully corrupted the Lord Admiral's mind and soul. With help from the few most sympathetic thaumaturges he ended the plunder and destruction and updated the Byzantine Plan or the Mehmed Plan, which will see the return of the Byzantine Empire albeit in a reduced state should the Roman Exodus be made a failure; this plan, once successful, is also made to enrage the Lord Admiral and let him know how fallen have he become.
Only in 1921 did the Byzantine Empire return, now currently composed solely of Constantinople and the three neighboring provinces. When Borealis I learned of Byzantium's return he was driven in a hate-filled frenzy which required members of the Lord Admiral's Elite Guard (then disguised as members of the US Navy) to restrain him. Currently, the Byzantine Empire is a UN-recognized sovereign entity and a member state of the United Nations.
In 2015, after the end of the Godom War, the arrival of a few ships from another Earth ultimately revealed the true fate of the Byzantine Empire: the defenders and peoples of Constantinople, Epiros, Theodoro, Morea and Trezibond were successful in the evacuation and became the Elysian Empire, Kingdom of Spartania and Republic of Kauka.