For pic. see http://www.villagehatshop.com/art_clemente_zapatistas.html
Painted 1931, now in the Museum of Modern Art, New York.
For the point in his work/and who he is representing you will need to look up a little Mexican history http://www.cs.utk.edu/~miturria/project/zapata.html and read about the Mexican Revolution and Emiliano Zapata, Father of the Zapatista Movement
This picture shows a group of his supporters - the Zapatistas going into battle.
There are no specific texts on the web about this picture. But don't despair: if you know who these people are- and a little about this group, then all you need is to study the the picture it tells you everything. (By the way, note the distinctive Mexican clothing, especially the hats which gives the picture a special flavor.). Oroczo painted it as proganda for this movement - he gets over the strength and determination of the Zapata 'soldiers" (also women) by the repetition of figures and the bayoneted rifles becoming a pattern of diagonals. This pattern contrasts straight and curved forms; the contrast of warm and cool colors. The result is a forceful composition.
José Clemente Orozco (b.1883,-d. 1949) was a Mexican social realist painter who specialized in murals. Zapatistas is however an oil on canvas painting (45x55 inches) .