The Quemoy and Matsu island group, situated in the Taiwan strait between the main island of Taiwan and the Chinese mainland, was the first line of defense for the Republic of China (ROC)-the Nationalist government on Taiwan-against the Communist government of the People's Republic of China, and had been highly fortified by the ROC since Chiang Kai-shek's retreat to Taiwan in 1949. On August 23, 1958, the Communist forces began an intense artillery bombardment of Quemoy. ROC forces in Quemoy dug in and returned fire. The Eisenhower administration responded to the ROC's request for aid according to its obligations in the 1954 U.S.-ROC defense treaty by reinforcing U.S. naval units and ordering U.S. naval vessels to help the ROC government enforce a naval blockade to protect Quemoy's supply lines. The crisis finally ended with a ceasefire on October 6. This study, most of which was declassified by the Defense Department in 1975, presents a comprehensive and detailed account of the crisis. The author had access to classified U.S. government papers at the Departments of Defense and State and consulted written materials from the Commander in Chief of the Pacific Fleet and the Taiwan Defense Command in Taipei. Additionally, he interviewed most of the leading decisionmakers who participated in national policymaking at the time.