Unify
Unify (verb) /ˈjuː.nɪ.faɪ/
to unite and bring together – form a single unit, join, combine, merge, amalgamate, bring together, fuse
We need to bury the hatchet and unify our forces to regain our power.
Antonym: separate
Noun: unification
Noun: unifier
Adjective: unifiable
Adjective: unifying