Complex sentence: Collectively the movement was called the "Ejército Constitucionalista de México" (Constitutionalist Army of Mexico), the "Constitucionalista" adjective was added to stress the point that Huerta had not legally obtained power through lawful avenues laid out by Mexico's Constitution of 1857.
Split into simpler sentences: Collectively the movement was called the "Ejército Constitucionalista de México" (Constitutionalist Army of Mexico). The "Constitucionalista" adjective was added to stress the point that Huerta had not legally obtained power through lawful avenues laid out by Mexico's Constitution of 1857.