4·19 혁명
In July 1950, he returned to Nicaragua, where he participated in the 1954 April Revolution against Anastasio Somoza García's regime. The coup d'état failed and ended with the deaths of many of his associates. After a deep mystical experience that Cardenal had on June,2, 1956, in 1957 he entered the Trappist Monastery of Gethsemani (Kentucky, United States), joining another poet-priest, Thomas Merton, who was the master of novices; but in 1959, he left to study theology in Cuernavaca, Mexico.