United Nations Conference on International Organization
After World War II, Manahan assisted in the editing and publication of the Free Philippines, a political paper. Later, he published three Manila newspapers, namely: the "Liberty News" (English daily), "Bagong Buhay" (Tagalog daily), and "La Voz de Manila" (Spanish publication). In 1945, he also served as the representative of the Philippine press at the United Nations Conference on International Organization in San Francisco.