The siege of Adrianople (Bulgarian: o , Serbian: o , Turkish: Edirne kuatmas), was fought during the First Balkan War. The siege began on 3 November 1912 and ended on 26 March 1913 with the capture of Edirne (Adrianople) by the Bulgarian 2nd Army and the Serbian 2nd Army.

The loss of Edirne delivered the final decisive blow to the Ottoman army and brought the First Balkan War to an end. A treaty was signed in London on 30 May. The city was reoccupied and retained by the Ottomans during the Second Balkan War.The victorious end of the siege was considered to be an enormous military success because the city's defenses had been carefully developed by leading German siege experts and called 'undefeatable'. The Bulgarian army, after five months of siege and two bold night attacks, took the Ottoman stronghold.

The victors were under the overall command of Bulgarian General Nikola Ivanov while the commander of the Bulgarian forces on the eastern sector of the fortress was General Georgi Vazov, the brother of the famous Bulgarian writer Ivan Vazov and of General Vladimir Vazov.

The early use of an airplane for bombing took place during the siege; the Bulgarians dropped special hand grenades from one or more airplanes in an effort to cause panic among the Ottoman soldiers. Many young Bulgarian officers and professionals who took part in this decisive battle would later play important roles in Bulgarian politics, culture, commerce and industry.

The Balkan Wars consisted of two conflicts that took place in the Balkan States in 1912 and 1913. Four Balkan states defeated the Ottoman Empire in the First Balkan War. In the Second Balkan War, Bulgaria fought against all four original combatants of the first war. It also faced an attack from Romania from the north. The Ottoman Empire lost the bulk of its territory in Europe. Although not involved as a combatant, Austria-Hungary became relatively weaker as a much enlarged Serbia pushed for union of the South Slavic peoples. The war set the stage for the Balkan crisis of 1914 and thus served as a "prelude to the First World War".By the early 20th century, Bulgaria, Greece, Montenegro and Serbia had achieved independence from the Ottoman Empire, but large elements of their ethnic populations remained under Ottoman rule. In 1912, these countries formed the Balkan League. The First Balkan War began on 8 October 1912, when the League member states attacked the Ottoman Empire, and ended eight months later with the signing of the Treaty of London on 30 May 1913. The Second Balkan War began on 16 June 1913, when Bulgaria, dissatisfied with its loss of Macedonia, attacked its former Balkan League allies. The more numerous combined Serbian and Greek armies repelled the Bulgarian offensive and counter-attacked into Bulgaria from the west and the south. Romania, having taken no part in the conflict, had intact armies to strike with and invaded Bulgaria from the north in violation of a peace treaty between the two states. The Ottoman Empire also attacked Bulgaria and advanced in Thrace regaining Adrianople. In the resulting Treaty of Bucharest, Bulgaria conserved most of the territories it had gained in the First Balkan War. However, it was forced to cede the ex-Ottoman south part of Dobruja province to Romania.The Balkan Wars were marked by ethnic cleansing with all parties being responsible for grave atrocities against civilians and helped inspire later atrocities including war crimes during the 1990s Yugoslav Wars.