If you commit violence without an achievable end, it's not rebellion; it's just murder. That means any violence needs to be directed by a well-organized entity that operates, functionally, as a rival government.
In the Colonies, that was the Continental Congress. In the American Civil War, that was the Confederate States of America. (I oppose the CSA completely, but they certainly were capable at coordinating violence to achieve their goals of slavery and disunion.) In the French Revolution, the Third Estate. In various English civil wars, rival claimants to the throne, with rival courts and rival bureaucracies. In the Russian Revolution, the Communist Party was arguably already the most functional government in Russia.
I don't think the entity *has* to be a government or quasi-government *necessarily*, but, in practice, it nearly always is. What you *do not* want is to create a situation like The Troubles, where there's sporadic murder but no movement toward a resolution, and that's usually what you get from terrorism unsupported by a government or quasi-government.
https://www.marxists.org/archive/lenin/works/1901/witbd/https://www.marxists.org/archive/lenin/works/1917/apr/09.htm