Catholic Culture.Org has an article by Christopher Check who gives an overview of the incredible story of The Cristeros. These Catholic peasants were the subject of the recent film - For Greater Glory starring Andy Garcia, Eva Longoria, Peter O'Toole, Bruce McGill, Ruben Blades, and Eduardo Verastegui.
This summary of the article gives the overview-
"Less than a century ago, the devoutly Catholic population of Mexico was de-Christianized by atheistic revolutionaries who declared war on the Catholic Church. Citizens who refused to comply were captured, tortured, and violently murdered. In this article, Christopher Check provides an excellent overview of the Cristero cause and how they restored the Catholic faith to Mexico."