Rebel groups have taken Syria’s second-biggest city. Here’s who they are

The city you’re referring to could likely be Aleppo, which was taken over by various rebel groups in 2012 during the ongoing Civil War in Syria. The main rebel groups that were involved in taking over the city were:

1. Free Syrian Army (FSA): Initially composed mostly of defectors from the Syrian military, the FSA was one of the earliest opposition groups. However, by the time of the Battle of Aleppo, it was a loose coalition of different factions, rather than a unified force.

2. Jabhat al-Nusra: Also known as the Nusra Front, this is a radical Islamist group that was originally an affiliate of Al-Qaeda. They split from the terrorist organization in 2016, and changed their name to Hayat Tahrir al-Sham.

3. Ahrar al-Sham: Another Islamist group, Ahrar al-Sham has been one of the most powerful rebel factions in Syria. They have a more nationalistic than global jihadist ideology, and had a significant presence in Aleppo.

4. ISIS (self-proclaimed Islamic State): This globally infamous extremist organization also had a presence in Aleppo, but was not as dominant here as in Raqqa, their self-claimed capital in Syria.

Bear in mind that the situation in Syria is extremely dynamic, with alliances shifting frequently, and that this information might have changed depending on the context and the timeline.