militancy

aggressive activism or combativeness in supporting or agitating for a cause: Many labor experts credit the early militancy of the Industrial Workers of the World as leading to the eight-hour work day.

the act of engaging or readiness to engage in war or armed aggression: In September 1914, Planck signed the "Manifesto of 93 German intellectuals to the civilized world" in support of the growing militancy of Germany.