The siege of Aleppo refers to a military operation conducted by forces of the Syrian government led by Hafez al-Assad in 1980 during the armed conflict between the Sunni groups, including the Muslim Brotherhood, and the Syrian government. Government forces committed several massacres in the course of the operation. Background Protests and violence Aleppo has traditionally been seen as Syria's most important city after Damascus, and was an important center to members of Syria's democratic and secular opposition as well as the armed Islamist opposition. The city was the scene of the Aleppo Artillery School massacre in June 1979, and also witnessed running battles and clashes between government security forces and the Islamist opposition in Autumn 1979. Armed cells of radical Islamist opposition attacked police patrols and government as a result, Syrian's government military and security forces launched a crackdown resulting in many casualties. Government security forces clamped down on the opposition, raiding opposition centers and meeting places. Government security forces were composed of 5,000 soldiers of the Defense Brigades, as well as thousands of members of the police and various other state security organizations. In spite of the heavy government presence large sections of Aleppo fell out of the control of the Syrian state. Surge in opposition activity Violence in the city exploded in November 1979, after security forces arrested Shaykh Zain al-Din Khairalla, a leading voice amongst Islamists and a regular leader of Friday prayers in the Great Mosque of Aleppo. Following the arrest opposition activity and violence increased exponentially, with daily demonstrations, strikes, and boycotts, and increased attacks on Ba'ath Party offices. The Islamist opposition were the biggest threat to the state, as they were the best armed and organized, although the secular opposition threatened the Ba'athist state due to its wide support amongst the middle classes, as well as minority groups opposed to the Islamists. Operation Crackdown In early March 1980 the Syrian Muslim Brotherhood closed down the business district of Aleppo for two weeks. The strikes spurred sympathy strikes in other cities including Hama, Homs, Idlib, Deir ez-Zor, and Hasaka. In response both to the strikes and the general increase in opposition activity, in mid March units of the 3rd Division of the Syrian Army were redeployed to Aleppo from Damascus and Lebanon. The Division was reinforced with Special Forces units as well as additional units of the Defense Brigades. Syrian government forces, comprising some