South Viet Nam: Durable Diem

At 7 a.m., in the second-floor study of Saigon's yellow stucco Freedom Palace, South Viet Nam's President Ngo Dinh Diem was absorbed in a biography of George Washington, the gift of a recent U.S. visitor. At the sudden roar of an airplane engine, he looked up, hurried out to the balcony in time to see a fighter plane swooping toward him through the early morning overcast.

Scarcely 16 months ago, autocratic, anti-Communist President Diem had narrowly missed being overthrown by mutinous paratroopers, and this time he was taking no chances. With the agility born...