Army of the Three Guarantees
While different standards and flags were used during the pre-Hispanic period, the viceroyalty, and the Mexican War of Independence, the modern flag has its origins in the flag of the Army of the Three Guarantees in 1821. Today it consists of a rectangle with a green stripe on the left (signifying the Independence Movement), a white stripe in the middle (originally signifying the purity of the Catholic faith), and a red stripe on the right (signifying the blood of the fighters). There is a coat of arms in the center.