Historically charged term. Most often refers to either the
国民革命军 (Guómín Gémìngjūn, National Revolutionary Army, 1925-1947, Sun Yat-sen / Chiang Kai-shek's KMT forces in the Northern Expedition and War of Resistance) or generic Xinhai-era anti-Qing forces.
邹容 (Zōu Róng) wrote the influential 1903 pamphlet 《
革命军》, a manifesto that helped spark the 1911 revolution.