Zemun is a municipality in the city of Belgrade, Serbia. Zemun was a separate town that was absorbed into Belgrade in 1934. It lies on the right bank of the Danube river, upstream from downtown Belgrade. The development of New Belgrade in the late 20th century expanded the continuous urban area of Belgrade and merged it with Zemun.

The siege of Belgrade was a successful attempt by Austrian troops under the command of Prince Eugene of Savoy to capture the strategically important city of Belgrade from the Ottoman Empire. It took place during the Austro-Turkish War (1716–1718), barely a year after the Austrian victory at the Battle of Petrovaradin (Peterwardein). The Imperial Army routed the Ottoman relief army under Grand Vizier Hacı Halil Pasha on 16 August. As a consequence, the Belgrade garrison, deprived of relief, surrendered to the Austrians on 21 August. The Ottoman Sultan Ahmed III sued for peace, resulting in the Treaty of Passarowitz a year later, which completed the transfer of the remainder of Hungary, the Banat and the city of Belgrade into Austrian hands.