August 1452 · Bosphorus Strait Theater

As his first act of war, Mehmed II ordered the construction of Rumeli Hisarı — the Throat-Cutter fortress — on the European shore of the Bosphorus, directly across from the older Anatolian fortress of Anadolu Hisarı. Built in just four months by an army of workers and completed in August 1452, the twin fortresses gave the Ottomans complete control of the Bosphorus strait and cut off Constantinople from Black Sea supplies. When a Venetian supply ship refused to stop and attempted to run the strait, Ottoman cannon fire sank it and the crew was executed. Mehmed had closed the city's supply lines before a single shot was fired at its walls.

April 6–11, 1453 · Theodosian Land Walls, Constantinople Theater

Mehmed's great bombards — including the massive 'Urban Gun' capable of firing 600-pound stone cannonballs — opened fire on the Theodosian Walls that had protected Constantinople for a thousand years. The walls, built in the 5th century and never successfully stormed, were designed for the pre-gunpowder era. The bombards fired seven to fourteen rounds per day; each shot took hours to cool, reload, and aim. The walls cracked and crumbled under the impact — but Byzantine defenders worked through each night to fill the breaches with earth, timber, and rubble, restoring an improvised defense by dawn. The initial bombardment did not breach the walls permanently, but it began an irreversible structural degradation.

April 18, 1453 · Gate of St. Romanos, Land Walls Theater

After artillery had opened a breach in the Lycus Valley sector of the walls, Mehmed ordered a major night assault on April 18. Ottoman infantry — Bashi-bazouks and Anatolian regulars — streamed through the darkness and attacked the damaged sections. Giustiniani organized a fierce counterattack that pushed the Ottoman forces back from the breaches, and Byzantine cannon fire and Greek fire inflicted heavy casualties on the attackers climbing the rubble. After four hours of intense fighting, Mehmed ordered the withdrawal. The first attempt to storm the city had failed.

April 20, 1453 · Sea of Marmara / Bosphorus entrance Theater

Three Genoese supply ships and one Byzantine vessel attempted to run the Ottoman naval blockade and reach Constantinople with supplies, helped by a favorable wind. The Ottoman fleet — 145 ships — attempted to stop them. In a remarkable engagement, the four large sailing ships used their height advantage and superior firepower to beat off attack after attack from the smaller Ottoman galleys, which could not board them effectively. With the wind dying, they became becalmed just short of the Golden Horn. Watching from the shore with his entire army, Mehmed was reportedly so furious that he rode his horse into the surf, screaming at his admirals. Eventually an evening wind brought the four ships safely into the harbor — the last successful resupply of Constantinople.

April 22, 1453 · Galata to Golden Horn, via dry land Theater

Unable to force his navy through the chain blocking the Golden Horn entrance, Mehmed executed one of the most audacious logistics operations in siege history: he had 70 ships dragged overland on greased wooden rollers, across the Galata hill and down the other side into the Golden Horn. The operation was conducted overnight to maximize surprise. Dawn revealed an Ottoman fleet already assembled within the harbor, threatening the northern walls that had never required serious defense. The Byzantine garrison — already desperately thin — now had to split its forces. A Venetian plan to fire-bomb the transported fleet was betrayed to the Ottomans, and the attack failed.

May 7, 1453 · Multiple Wall Sectors, Constantinople Theater

The second major assault targeted multiple wall sections simultaneously, forcing the defenders to split their already-thin resources. Zaganos Pasha's troops attacked from within the Golden Horn. The Anatolian corps struck the land walls near the Blachernae sector. Mehmed's elite Janissaries attacked the primary breach in the Lycus Valley. For three hours the defenders held, repulsing assault after assault in brutal close-quarters combat. Constantine XI himself fought at the breach with his household guard. By dawn, the second assault had failed — but the defenders had suffered casualties they could not replace.

May 16–23, 1453 · Blachernae Palace sector, northern walls Theater

Unable to breach the Blachernae sector walls with artillery alone, Ottoman engineers — including Serbian miners from Novo Brdo — began digging tunnels beneath the walls to collapse them from below. Byzantine defenders, led by the Scottish engineer Johannes Grant (serving the Emperor), counter-mined: digging parallel tunnels, listening for the sound of Ottoman digging through bowls of water placed on the ground, then breaking into the Ottoman tunnels and fighting them underground. At least six tunnels were discovered and neutralized — Byzantine troops fought the miners in complete darkness, collapsed their tunnels with smoke and fire, or flooded them with water. Every Ottoman mining attempt failed.

May 22, 1453 · Sea Walls of Marmara coast Theater

A total lunar eclipse on the night of May 22 terrified the Byzantine defenders — an ancient prophecy held that Constantinople would fall when the moon was full. The Ottomans launched coordinated attacks on the sea walls by both the Golden Horn fleet and the Marmara sea approach, while simultaneously renewing artillery bombardment of the land walls. Byzantine sailors held the sea walls with incendiary weapons and concentrated missile fire. The defenders repulsed the seaborne attacks, but the eclipse's psychological damage was severe: morale collapsed in the city as the population interpreted the darkened moon as divine confirmation of doom.

May 29, 1453 · Theodosian Walls, Gate of St. Romanos, Constantinople Theater

Mehmed ordered the final assault for the predawn hours of May 29. He sent wave after wave — first the Bashi-bazouks (irregular light troops, used to exhaust the defenders), then the Anatolian regulars, finally the Janissaries, his elite household troops, who had been kept fresh throughout. During the Janissary assault, Giovanni Giustiniani was struck by a crossbow bolt or gunshot and was carried wounded from the walls — his departure, visible to the defenders, triggered panic. A small unguarded gate — the Kerkoporta — was found open and Ottoman troops flooded in. Constantine XI, seeing the walls breached and his commander gone, reportedly tore off his imperial insignia, drew his sword, and charged into the mass of Ottoman soldiers. He was never seen alive again. By mid-morning, the city had fallen.

May 29 – June 1, 1453 · Constantinople, throughout the city Theater

Following the custom of the time — and his promise to his troops — Mehmed permitted three days of plunder. The sack lasted approximately one day before Mehmed entered the city personally and ordered it stopped. Ottoman soldiers ransacked churches, palaces, and private homes; thousands of civilians were killed or enslaved; priceless manuscripts, icons, and relics were destroyed or dispersed across the Ottoman world. When Mehmed reached the Hagia Sophia — the greatest church in Christendom — he reportedly wept at its beauty, rebuked a soldier for breaking the marble floor, and immediately ordered its conversion to a mosque. He claimed the title 'Caesar of Rome' and announced that Constantinople would be the new capital of his empire.