Murad II in the context of "Ghazis"

Gjergj Kastrioti (c. 1405 – 17 January 1468), commonly known as Skanderbeg, was an Albanian nobleman and military leader who led the League of Lezhë in the Ottoman-Albanian Wars until his death. Skanderbeg is considered to be a major figure of medieval Albanian history and today is the national hero of Albania.

A member of the noble Kastrioti family, Skanderbeg was sent as a hostage to the Ottoman court. He graduated from the Enderun School and entered the service of the Ottoman sultan Murad II (r. 1421–1451) for the next twenty years. His rise through the ranks culminated in his appointment as sanjakbey of the Sanjak of Dibra in 1440. During the Battle of Nish in 1443, he deserted the Ottomans and became the ruler of Krujë and nearby areas extending from Petrelë to Modrič. In March 1444, he established the League of Lezhë, with support from local noblemen, and unified the Albanian principalities.

The Battle of Nish (early November 1443) was fought between the Crusaders led by John Hunyadi and Đurađ Branković and the Ottoman Empire led by Kasım Pasha. It saw the Crusaders capture the Ottoman stronghold of Nish (Niš) in Serbia, and defeat two armies of the Ottoman Empire. The Battle of Nish was part of Hunyadi's expedition known as the long campaign. Hunyadi, at the head of the vanguard, crossed the Balkans through the Gate of Trajan, captured Nish, defeated three Ottoman pashas, and after taking Sofia from the Ottomans, united with the royal army and defeated Sultan Murad II at Snaim (Kustinitza). The impatience of the king and the severity of the winter then compelled him (in February 1444) to return home.

The Treaty of Edirne and the Peace of Szeged were two halves of a peace treaty between Sultan Murad II of the Ottoman Empire and King Vladislaus of the Kingdom of Hungary. Despot Đurađ Branković of the Serbian Despotate was a party to the proceedings. The treaty brought an end to the Christian crusade against the Ottomans with significant gains. Within a month Vladislaus abjured his oath at the urging of the papacy and the crusade continued. On 10 November 1444 it ended in disaster at the Battle of Varna where the crusaders were wiped out and Vladislaus killed.

The treaty was started in Edirne with discussions between Murad and Vladislaus' ambassador. Within a few days, it was sent to Szeged with Murad's ambassador, to be finalized and ratified by Vladislaus. Once it arrived, complications caused the negotiations to continue for several more days, and oaths were eventually given in Várad. The ratification took place on 15 August 1444 in Várad.

A janissary (UK: /ˈdʒænɪsəri/ JAN-iss-ər-ee, US: /-sɛri/ -⁠err-ee; Ottoman Turkish: یڭیچری, romanized: yeñiçeri, IPA: [jeˈŋit͡ʃeɾ̞i], lit. 'new soldier') was a member of the elite infantry units that formed the Ottoman sultan's household troops. They were the first modern standing army, and perhaps the first infantry force in the world to be equipped with firearms, adopted during the reign of Murad II (r. 1421–1444, 1446–1451). The corps was established under either Orhan or Murad I, and dismantled by Mahmud II in 1826.

Janissaries began as an elite corps made up through the devşirme system of child levy enslavement, by which Christian boys, chiefly from the Balkans, were taken, levied, subjected to forced circumcision and forced conversion to Islam, and incorporated into the Ottoman army. They became famed for internal cohesion cemented by strict discipline and order. Unlike typical slaves, they were paid regular salaries. Forbidden to marry before the age of 40 or engage in trade, their complete loyalty to the Ottoman sultan was expected. By the 17th century, due to a dramatic increase in the size of the Ottoman standing army, the corps' initially strict recruitment policy was relaxed. Civilians bought their way into it in order to benefit from the improved socio-economic status it conferred upon them. Consequently, the corps gradually lost its military character, undergoing a process that has been described as "civilianization".

The siege of Thessalonica between 1422 and 1430 saw the Ottoman Empire, under Sultan Murad II, capture the city of Thessalonica. Afterwards, the city 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 Çelebi, a rival pretender against him, Murad, attacked Thessalonica. Unable to provide manpower or resources for the city's defence, its ruler, Andronikos Palaiologos, handed it over to the Republic of Venice in September 1423. The Venetians attempted to persuade the Sultan to recognise 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.