Constantinople Rescue

Context

By the mid-15th Century, the constant struggle for dominance between its Balkan neighbours and Roman Catholic opponents had reduced Byzantine Empire holdings in Constantinople and land to the west. Constantinople’s population dropped from 400,000 in the 12th Century to 40,000-50,000 by the mid-1450s. This was due to the many devastating sieges that the city had endured. The vast open fields covered much of the area within the walls. Byzantine relations had soured with the rest of Europe over the past several centuries. The Schism in 1054, and the 13th-century Latin occupation of Constantinople had entrenched mutual hatred between Orthodox Byzantines. The Byzantines’ control of Constantinople, however, was equally firmly entrenched as a necessary bastion to counter the Muslim control over land and sea along the eastern Mediterranean.

The Ottoman Turks extended their control to almost all of the Balkans as well as most of Anatolia after conquering several Byzantine towns west of Constantinople during the second half of the 14th Century. During this time, Constantinople became an Ottoman vassal. Hungary was the main European threat on land to the Ottomans, while Venice and Genoa controlled most of the Aegean Sea and Black Sea. Sultan Murad 2 laid the siege on Constantinople in 1402 but was forced to lift it to suppress a revolt elsewhere in his empire. In 1444, he lost a major battle in the Balkans to a Christian coalition and abdicated his throne. He returned to power after defeating Christians two years later and remained Sultan until he died in 1451.

Mehmed I, now sultan a second time intended to complete the mission of his father and conquer Constantinople. In 1452, he signed peace treaties with Hungary as well as Venice. To limit the passage between the Black Sea and the Mediterranean, he also started the construction of Bogazkesen. (Later called Rumelihisari), which is a fortress located in the narrowest part of the Bosporus. Mehmed tasked Hungarian gunsmith Urban to both arm Rumelihisari as well as build a cannon strong enough to bring the walls of Constantinople down. Urban’s cannon was transported to Constantinople from the Ottoman capital Edirne by March 1453. After capturing Byzantine coastal towns along the Black Sea, Sea of Marmara and Rumelia, Ottoman regiments from Anatolia and Rumelia gathered outside the Byzantine Capital in April. The Fleet moved to Diplokionion from Gallipoli, and the Sultan himself went to meet his army.

The Byzantine Emperor Constantine XI Palaeologus appealed to the major powers of Christendom for help in the imminent siege. Hungary refused to help, and instead of sending troops, Pope Nicholas VI used the situation to press for the unification of Orthodox and Roman Catholic Churches, which had been a priority to the papacy ever since 1054. The Orthodox Church leaders voted for union but the people in Constantinople were against it. They rioted. Venetian and Genoese military support was provided. The Venetian Senate, prompted by an Ottoman attack against a Venetian vessel in the Bosporus, sent 800 troops and 15 galleries to Constantinople. Many Venetians in Constantinople chose to join the war effort as well, but most of their forces had been delayed too long for them to be much help. The city-state of Genoa sent 700 soldiers, led by Giovanni Giustiniani Longo, to Constantinople in January 1453. Giustiniani was appointed commander of Constantine XI’s land defences. He spent the winter preparing the city to be sieged.

Battle

The walls of Constantinople were widely regarded as being the strongest in Europe during the 15th century. The walls were 4 miles long (6.5 km), and had a double row of wall ramparts on the outside. The tallest of these was 40 feet (12 meters) high, with a base up to 16 feet (5 m) thick. The walls have never been breached during the 1000 years since they were built. A sea wall was built along the Golden Horn and Sea of Marmara. The latter section of the wall measured 20 feet (6 meters) in height and 8 km (5 miles) in length. Constantine believed that the city defences would be able to repel an attack from the sea and Mehmed’s forces on land until help arrived from Christian Europe. Constantine was limited in his ability to defend the city by his small force. Jacopo Tedaldi, an eyewitness, estimates that there were between 30,000 and 35,000 armed civilians present. However, only 6,000-7,000 soldiers had been trained. Giustiniani planned to concentrate the majority of these men along the walls of the city to the north and the west. He observed that the centre of this wall was the most vulnerable area of the town. To defend the Golden Horn, a small fleet of armed merchant ships and naval vessels was also stationed. Constantinople would be weakened if it did not receive outside assistance.

The Ottomans outnumbered the Byzantines and their allies. Between 60,000 to 80,000 soldiers, along with 69 cannons, fought on the land. Baltaoglu Bey was in charge of a fleet at Diplokionion, which consisted of 31 warships and smaller vessels. Mehmed had a simple strategy: he’d use his fleet to blockade Constantinople from all sides while pounding its walls with cannons. He wanted to breach the walls or force a surrender before Christian relief forces could arrive.

The Ottomans started their artillery on April 6 and brought down part of the wall. On April 7, they launched a frontal attack on the land walls but were repulsed by the Byzantines who repaired the defences. Mehmed, after repositioning his cannon and pausing for a moment to do so, reopened the fire. He continued daily bombardment.

The fleet was twice driven back, and Baltaoglu retreated to Diplokionion until the night of April 17, when he moved to capture the Princes Islands southeast of the city at the same time that Mehmed’s land regiments assaulted the Mesoteichon section. Baltaoglu was forced to retreat to Diplokionion twice, then he attacked the Princes Islands to the southeast of the city on the night of April 17. Mehmed’s land regiments were also attacking the Mesoteichon portion of the wall. Baltaoglu was unable to capture the islands, as Constantinople’s defences held firm. Baltaoglu also suffered a setback when he learned that three relief vessels from the pope, along with a large Byzantine vessel, had almost reached the city. Ottoman galleys could not capture tall European warships. With the assistance of the Golden Horn Fleet, the ships safely passed the chain. Mehmed, upon hearing the news of his navy’s loss, stripped Baltaoglu of his rank and made arrangements for his replacement.

Mehmed was determined that he would take the Golden Horn, and force the Byzantines to submit. He then built a wooden ramp, oiled and angled so that he could hit the defenders. This would allow him to move his smaller ships from the Bosporus into the Golden Horn. The ships were able to circumvent the chains by April 22, and had, except for the chain, taken control of the waters around the city. The defenders tried to attack the rest of the Ottoman Fleet in the Bosporus but were defeated.

Mehmed, having encircled Constantinople completely, continued to bombard the land walls with artillery until May 29. The Ottoman cannons created breaches but many were too narrow for troops to pass through. City defenders repaired the walls during the night and reinforced the areas near the Gate of St. Romanus as well as the Blachernae Sector. Ottoman workers filled the moat around the city in the early morning hours of May 29. Before dawn broke, the Sultan launched a coordinated assault of artillery, infantry and naval forces on Constantinople. Ottoman troops were forced to retreat after two failed attempts to storm the Blachernae and Gate of St. Romanus walls. Mehmed sent a third force of 3,000 janissaries to attack the gate. The defenders nearly wiped out a small group that had climbed to the top of the tower via another gate. Giustiniani, however, was fatally injured while on the ramparts. His absence confused and reduced morale in the ranks. He was then carried back to the rear. The sultan was able to send another Janissary Regiment and capture the inner wall of the Gate of St. Romanus.

The defenders were beaten to a pulp, and many Venetians and Genoese retreated to their ships on the Golden Horn. The Emperor Constantine XI was reported to have died while fighting near the breach, or fleeing on an escape boat. The Sultan, although he tried to prevent the total sacking of the city allowed an initial period of looting which saw the destruction of many Orthodox Churches. Mehmed rode his horse through the streets to the Hagia Sophia cathedral, the largest of all the Christian churches, and transformed it into Ayasofya. The sultan stopped to pray and then ordered that the looting stop immediately. Thus, the sultan completed his conquest of the Byzantine capital.