I think both Austria and Brazil successfully fended off Communism by public prayer and penance.
Austria freed from Russian domination in 1955:
http://catholicgo.org/miracles-of-the-rosary-the-rosary-frees-austria-from-communist-rule-in-1955/
Brazil in 1962-1964:
http://catholicgo.org/miracles-of-the-rosary-the-rosary-saves-brazil-from-communism-1962-1964/
The article is a little loose with the facts.