Dahler was the only Indo who participated in the ‘Committee for the Study of Preparations for Independence’ (BPUPK) led by Sukarno and established by the Japanese in May 1945. After Indonesia's declaration of independence Dahler was a member of the political section of the Indonesian National Party (PNI). Together with independence leaders Sukarno and Sjahrir he continued to groom Indos to join the national revolution, but their efforts were undone by extremist revolutionary forces during the violent Bersiap period.