Written by Petrit Latifi.

Several sources discuss the role of Serbs in assisting the Ottoman Empire throughout history. Here are some key examples:

New World Encyclopedia notes that during the Ottoman rule, Serbs often cooperated with the Ottomans, especially as mercenaries and border guards in regions like Vojvodina under Hungarian rule. Serbian soldiers were integrated into Ottoman military campaigns and administrative roles.

Britannica highlights that Serbs were at times involved in Ottoman administrative structures and military campaigns. For instance, during the Austrian-Turkish War (1593–1606), Serbs in Banat staged uprisings but also found themselves intermittently collaborating with Ottoman forces depending on political and military contexts

These sources indicate that the relationship between Serbs and the Ottoman Empire was complex, involving both resistance and collaboration at different times and under various circumstances.

The conquest of Constantinople in 1453 by the Ottomans under the leadership of Sultan Mehmed II marked the end of the Byzantine Empire and was a pivotal moment in history. The role of the Serbs in this conquest was complex and multifaceted.

Vassal status and support:

• The Serbian Despot Đurađ Branković was a vassal of the Ottoman Empire at that time. After the Battle of Kosovo in 1389, Serbia had fallen into dependency on the Ottomans. Đurađ Branković and his predecessors had frequently sought Ottoman support in their internal conflicts and, in return, became vassals who had to pay tribute and provide military support. Source here.
  
• In the lead-up to the siege of Constantinople, Đurađ Branković provided the Ottomans with both troops and materials. Serbian engineers and miners were particularly involved in constructing the Ottoman siege engines, including the large cannons that were crucial for the success of the siege Source here and and here.

Military contributions:

• Serbian troops were part of the Ottoman army besieging Constantinople. These troops fought alongside other Ottoman units and played a role in the numerous assault waves against the city’s defenses. Source.
  
• A notable element was the Serbian artillery unit under the leadership of Master Orban, a Hungarian engineer supported by Đurađ Branković. Orban constructed some of the largest cannons of the time, which significantly contributed to breaching Constantinople’s formidable walls

Logistical support:

• The Serbs provided not only troops but also food, materials, and technical expertise. Supplying the Ottoman army during the protracted siege was a logistical challenge, eased by contributions from various vassal states Source here and here.

Political background:

• Đurađ Branković was in a difficult political situation, navigating between the Ottomans and the European powers, particularly the Holy Roman Empire and the Kingdom of Hungary. During the siege of Constantinople, he sought to strengthen his position by siding with the likely victor, the Ottomans Source here and here.
  
• Supporting the Ottomans was also a means for Đurađ Branković to secure his own rule in Serbia and maintain the autonomy of his principality within the Ottoman sphere of influence Source here.
  
  Conclusion
  
  In summary, the Serbs played a significant role in the conquest of Constantinople through their military, logistical, and technical support. Their involvement was a result of the complex political relationships and vassal obligations to the Ottomans, which required them to contribute to the Ottoman military campaigns Source here and here and here.