Battle of Aleppo (2012–2016)

The Battle of Aleppo (Arabic: مَعْرَكَةُ حَلَبَ, romanized: Maʿrakat Ḥalab) was a major military confrontation in Aleppo, the largest city in Syria, between the Syrian opposition (including the Free Syrian Army (FSA) and other largely-Sunni groups, such as the Levant Front and the al-Qaeda-affiliated al-Nusra Front) against the Syrian government, supported by Hezbollah, Shia militias and Russia, and against the Kurdish-majority People's Protection Units (YPG). The battle began on 19 July 2012 and was part of the ongoing Syrian Civil War. A stalemate that had been in place for four years finally ended in July 2016, when Syrian government troops closed the rebels' last supply line into Aleppo with the support of Russian airstrikes. In response, rebel forces launched unsuccessful counteroffensives in September and October that failed to break the siege; in November, government forces embarked on a decisive campaign that resulted in the recapture of all of Aleppo by December 2016. The Syrian government victory was widely seen as a turning point in Syria's civil war.

The large-scale devastation of the battle and its importance led combatants to name it the "mother of battles" or "Syria's Stalingrad". The battle was marked by widespread violence against civilians, repeated targeting of hospitals and schools (mostly by pro-government air forces and to a lesser extent by the rebels), and indiscriminate aerial strikes and shelling against civilian areas. It was also marked by the inability of the international community to resolve the conflict peacefully. The UN special envoy to Syria proposed to end the battle by giving East Aleppo autonomy, but this was rejected by the Syrian government. Hundreds of thousands of residents were displaced by the fighting and efforts to provide aid to civilians or facilitate evacuation were routinely disrupted by continued combat and mistrust between the opposing sides.

There were frequent instances of war crimes during the battle, including the use of chemical weapons by both Syrian government forces and rebel forces, the use of barrel bombs by the Syrian Air Force, the dropping of cluster munitions on populated areas by Russian and Syrian forces, the carrying out of "double tap" airstrikes to target rescue workers responding to previous strikes, summary executions of civilians and captured soldiers by both sides, indiscriminate shelling and use of highly inaccurate improvised artillery by rebel forces. During the 2016 Syrian government offensive, the UN High Commissioner for Human Rights warned that "crimes of historic proportions" were being committed in Aleppo.

After four years of fighting, the battle represents one of the longest sieges in modern warfare and one of the bloodiest battles of the Syrian Civil War, leaving over 31,000 people dead, almost a tenth of the estimated overall war casualties at that time. Fighting also caused severe destruction to the Old City of Aleppo, a UNESCO World Heritage Site. An estimated 33,500 buildings have been either damaged or destroyed. It is considered one of the worst urban battles fought in the 21st century, due to its length and destruction.