Events on March 29 in history

The Ottoman Empire under Murad II captures Thessalonica from the Republic of Venice.

The siege of Thessalonica between 1422 and 1430 saw the Ottoman Empire under Sultan Murad II capture the city of Thessalonica, which remained in Ottoman hands for the next five centuries, until it became part of the Kingdom of Greece in 1912.

Thessalonica had already been under Ottoman control from 1387 to 1403 before returning to Byzantine rule in the aftermath of the Battle of Ankara. In 1422, after the Byzantines supported Mustafa elebi as a rival pretender against him, Murad attacked Thessalonica. Unable to provide manpower or resources for the city's defense, its ruler, Andronikos Palaiologos, handed it over to the Republic of Venice in September 1423. The Venetians attempted to persuade the Sultan to recognize their possession, but failed as Murad considered the city his by right and the Venetians to be interlopers. This impasse led to an Ottoman blockade of Thessalonica, which occasionally flared up with direct attacks on the city. At the same time, the conflict was mostly fought as a series of raids by both sides against the other's territories in the Balkans and the Aegean Islands. The Venetians repeatedly tried to apply pressure by blocking the passage of the Dardanelles at Gallipoli, with little success.

The blockade quickly reduced the inhabitants to near starvation, and led many to flee the city. The restrictions placed on them by the siege, the inability of Venice to properly supply and guard the city, the violations of their customary rights, and rampant profiteering by Venetian officials led to the formation of a pro-surrender party within the city, which gained strength among the inhabitants. The city's metropolitan bishop, Symeon, encouraged his flock to resist. However, by 1426, with Venice's inability to secure peace on its own terms evident, a majority of the local population had come to prefer a surrender to avoid the pillage that would accompany a forcible conquest. Venice's efforts to find allies against the Ottomans also failed: the other regional potentates either pursued their own course, were themselves antagonistic to the Venetians, or were defeated by the Ottomans.

After years of inconclusive exchanges, the two sides prepared for a final confrontation in 1429. In March, Venice formally declared war on the Ottomans, but even then the conservative mercantile aristocracy running the Republic were uninterested in raising an army sufficient to protect Thessalonica, let alone to force the Sultan to seek terms. In early 1430, Murad was able to concentrate his forces against Thessalonica, taking it by storm on 29 March 1430. The privations of the siege and the subsequent sack reduced the city to a shadow of its former self, from perhaps as many as 40,000 inhabitants to c.2,000, and necessitated large-scale resettlement in the following years. Venice concluded a peace treaty with the Sultan in July, recognizing the new status quo. Over the next few decades, the antagonism between Venice and the Ottomans morphed into a rivalry over control of Albania.

The Ottoman Empire (; Ottoman Turkish: دولت عليه عثمانيه Devlet-i ʿAlīye-i ʿOsmānīye, lit. 'The Sublime Ottoman State'; Turkish: Osmanlı İmparatorluğu or Osmanlı Devleti; French: Empire ottoman) was an empire that controlled much of Southeastern Europe, Western Asia, and Northern Africa between the 14th and early 20th centuries. It was founded at the end of the 13th century in northwestern Anatolia in the town of Söğüt (modern-day Bilecik Province) by the Turkoman tribal leader Osman I. After 1354, the Ottomans crossed into Europe and with the conquest of the Balkans, the Ottoman beylik was transformed into a transcontinental empire. The Ottomans ended the Byzantine Empire with the conquest of Constantinople in 1453 by Mehmed the Conqueror.Under the reign of Suleiman the Magnificent, the Ottoman Empire marked the peak of its power and prosperity, as well as the highest development of its governmental, social, and economic systems. At the beginning of the 17th century, the empire contained 32 provinces and numerous vassal states. Some of these were later absorbed into the Ottoman Empire, while others were granted various types of autonomy over the course of centuries. With Constantinople (modern-day Istanbul) as its capital and control of lands around the Mediterranean Basin, the Ottoman Empire was at the centre of interactions between the Middle East and Europe for six centuries.

While the empire was once thought to have entered a period of decline following the death of Suleiman the Magnificent, this view is no longer supported by the majority of academic historians. The newer academic consensus posits that the empire continued to maintain a flexible and strong economy, society and military throughout the 17th and for much of the 18th century. However, during a long period of peace from 1740 to 1768, the Ottoman military system fell behind that of their European rivals, the Habsburg and Russian empires. The Ottomans consequently suffered severe military defeats in the late 18th and early 19th centuries. The successful Greek War of Independence concluded with decolonization of Greece following the London Protocol (1830) and Treaty of Constantinople (1832). This & other defeats prompted the Ottoman state to initiate a comprehensive process of reform and modernization known as the Tanzimat. Thus, over the course of the 19th century, the Ottoman state became vastly more powerful and organized internally, despite suffering further territorial losses, especially in the Balkans, where a number of new states emerged.The Committee of Union and Progress (CUP) established the Second Constitutional Era in the Young Turk Revolution in 1908, turning the Empire into a constitutional monarchy, which conducted competitive multi-party elections. However, after the disastrous Balkan Wars, the now radicalized and nationalistic CUP took over the government in the 1913 coup d'état, creating a one party regime. The CUP allied the Empire with Germany hoping to escape from the diplomatic isolation which had contributed to its recent territorial losses, and thus joined World War I on the side of the Central Powers. While the Empire was able to largely hold its own during the conflict, it was struggling with internal dissent, especially with the Arab Revolt in its Arabian holdings. During this time, genocide was committed by the Ottoman government against the Armenians, Assyrians, and Greeks. The Empire's defeat and the occupation of part of its territory by the Allied Powers in the aftermath of World War I resulted in its partitioning and the loss of its Middle Eastern territories, which were divided between the United Kingdom and France. The successful Turkish War of Independence, led by Mustafa Kemal Atatürk against the occupying Allies, led to the emergence of the Republic of Turkey in the Anatolian heartland and the abolition of the Ottoman monarchy.