Rebel or secessionist
A supporter of free-market economics is called a capitalist.
Generally, a supporter of any sports team is called a fan.
When a state left the Union it was called secession.
A term used for people who opposed secession of the states were called conservatives. The people that supported secession were called secessionists.
Secession
This is called a "strut" or "spar".
Secession
Secession .
Secession
Ideologist
The great Britain
Indeed. However, it is not called 'secession' but "Mexican Cession".