So is the rebellion essentially Sunni then?
It supposedly began as a protest for democratic & humanitarian reforms. The rebels against Assad are essentially Sunni, with some Kurds thrown in.
from Wiki : “A United Nations report in late 2012 described the conflict as being “overtly sectarian in nature”, between mostly Alawite government forces, militias and other Shia groups[86], fighting largely against Sunni-dominated rebel groups,[87][88] although both opposition and government forces have denied it.”
https://en.wikipedia.org/wiki/Syrian_Civil_War