Born 1919 in Turkey to a Greek mother and a Dutch father, Raymond Pierre Paul Westerling joined the Netherlands Army in 1941. In 1945 he was sent to the Netherlands East Indies, to assist in the suppression of a native rebellion by forces connected with Japan. After the close of the war, he formed the Angkatan Perang Ratu Adil (APRA), also known as the Prince Justice Legion as an organisation for the local inhabitants of the Netherlands East Indies who remained loyal to the Netherlands. The ideology of APRA gave primacy to Islam, the superiority of Malays over other ethnicities in the region, and even suggested a quasi-mystical role for Westerling as saviour of the greater Malay nation. This aspect of APRA ideology was based on an old Javanese legend that suggested a Turkish Messiah figure would usher in a period of universal peace.
APRA gained in power and prestige over the following decades. It's influence eventually spread across the region, with official branches in the Malay Trucial States allied with Great Britain, including in Sarawak and in the Malay diaspora throughout the British Empire. From the 1960s APRA also sponsored armed resistance by local Muslim Malays against the governments of Japan-allied Thailand and the Philippines, allied to the United States of America. By the late 1970s, Westerling himself was believed to have gone to the Southern Philippines to lead the anti-American crusade personally.