Although his missions were mostly successful, one of his mission caused him and his colleagues to be arrested by a Dutch patrol in Bintan at the end of 1948. Rais and his colleagues became prisoners of war in Gunung Kijang, Bintan Island, for almost a year. They were freed after a prisoner exchange agreement was reached between the Dutch and Indonesian parties at the Roem–Van Roijen Agreement in May 1949. A peace agreement was reached between the Dutch and Indonesian parties at the Round Table Conference.