Triumphal March into Mexico City

Source: Bradley Smith, Mexico: a History in Art. Garden City, N.Y.: Doubleday and Company, 1968, p. 206.
Image: "Entrance of the Army of the Three Guarantees", anonymous, 1821. Oil on canvas in the Museo Nacional de Historia, Chapultepec Castle, Mexico City
Humanities Questions: (A) Identify the style of this painting. (B) Identify the Mexican national colors. (C) What elements does the painter use to characterize the idea of a triumphal march into the capital?