Due to the outbreak of World War II, the school was forced to close for three years. Nevertheless, in September 1945, the school was reopened with a handful of teachers, holding classes in the bomb-shattered building. In July 1948, regular publication of The Cagayan Students' Chronicle which is the school organ of the Cagayan National High School up to this day, was resumed. In 1967 to 1972, the school was one of the ten pilot high schools in the country in teaching secondary English as a second language. As such, it was a regional center for the five-year English program.