Spies warned the Dutch about a planned revolt in 1926, and Communist Party of Indonesia (PKI) leaders were arrested. Andries Cornelis Dirk de Graeff replaced Dirk Fock as governor-general, and uprisings in Batavia, Banten, and Priangan were quickly crushed. Armed Communists occupied the Batavia telephone exchange for one night before they were captured. The Dutch sent prisoners to Banden and to a penal colony at Boven-Digoel in West New Guinea, where many died of malaria. Sukarno and the Study Club founded the Indonesian Nationalist Association (which became the Indonesian National Party and later joined the Partai Sarekat Islam, Budi Utomo, and the Surabaya Study Club to form the Union of Indonesian Political Associations) on 4 July 1927.