 Complete the following phrase:  Viên attended the French-run Cap Saint-Jacques Military School, graduating with a commission in the Vietnamese National Army as a second lieutet in 1949. He rose quickly through the ranks, becoming a battalion commander in 1953 and major in 1954. He attended the Vietnamese National Military Academy as a lieutet, where he met and became friendly with many of South Vietnams later military leaders. He twice served in military intelligence in 1953 and 1954, and twice as a military logistics officer. After the formation of the Army of the Republic of Vietnam ARVN in 1955, he was appointed chief of military logistics for the ARVN Joint General Staff. He graduated from the United States Army Command and General Staff College in 1957. By 1960, he had completed parachute training with both the Vietnamese and American military, earned his Vietnamese combat pilots license, and earned his American combat helicopter pilots license. Viên was promoted to lieutet colonel and appointed Chief of Staff of the Special Military Staff in the office of the President of the Republic in 1956. He and his family moved to a modest home in the Cholon neighborhood of Saigon where he lived until April 1975. He was promoted to colonel in 1960 and named Commander of the Vietnamese Airborne Division in November 1960. This came after Colonel Nguyễn Chánh Thi and Lieutet Colonel Vương Văn Đông, the two highest-ranking paratroopers led a 