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 by urban area, between the Syrian opposition militias (such as the Free Syrian Army (FSA), the Levant Front and Al-Nusra Front) against the Ba'athist Syrian government and army, supported by Russia, Iran, Hezbollah and other Shia militant groups backed by the IRGC, and other pro-government Syrian and Palestinian militias, and against the Kurdish-majority People's Protection Units (YPG). The battle began on 19 July 2012 and was part of the Syrian civil war. A stalemate that had been in place for four years finally ended in July 2016, when Ba'athist 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 government's siege of the rebel-held eastern half of the city; in November, government forces, allied with Russia and bolstered by YPG 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 the 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 but also to a lesser extent by the rebels), as well as indiscriminate bombardment and shelling of civilian areas from all sides. 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 rebel-held East Aleppo autonomy, but this was rejected by the Assad government. Hundreds of thousands of residents were displaced both internally and externally by the battle and efforts to provide aid to civilians or to facilitate evacuation were routinely disrupted by continued combat and mistrust between the opposing sides.

All parties to the battle have been widely condemned by the UN and human rights organizations for engaging in atrocities and violations of international humanitarian law. Pro-Assad forces and their allies engaged in indiscriminate aerial bombardment of residential neighborhoods, including systemically dropping barrel bombs and cluster munitions, as well as conducting "double-tap" airstrikes on civilians and rescue workers—a tactic mostly attributed to Russian aviation. Simultaneously, rebel factions indiscriminately targeted civilian areas with rocket and mortar attacks, including with improvised artillery that fired repurposed gas-canister mortars (or "hell cannons") conducted suicide car bombings, and were accused of using human shields by forcibly preventing civilians from leaving areas they controlled. Both government and opposition factions were accused of using chemical weapons executing forced displacement, engaging in torture and summary executions of civilians and POWs, and weaponizing starvation as a tactic of war by blockading food, medicine and other essentials from civilian populations at different points during the battle. Across front lines, government forces, opposition militias and the SDF were all implicated in sniper fire targeting civilians. Following the 2016 Ba'athist government offensive in Aleppo, the UN High Commissioner for Human Rights described the bombardments and devastating siege of East Aleppo as "crimes of historic proportions".

After four years of fighting, the battle was one of the bloodiest battles of the Syrian Civil War, leaving over 31,000 people dead in the city and the rest of the province, almost a tenth of the estimated overall war casualties at that time. The siege also resulted in the severe destruction of 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.