越战(1955～1975年)
Vietnam War
南越和美国为阻止北越共产党人在其领导下将南越与北越统一所作的长期而不成功的努力。第一次印度支那战争後，为了隔离敌对兵力，於1956年举行自由选举。目的是重新统一南北越。北越由於已在越南两部分加强其广大的政治组织，因而可望赢得这次选举。但已在南越巩固其控制的吴廷琰拒绝已排定的选举。游击战随着在北越受训和武装起来的士兵－－越共－－对抗由美国支持的南越。1968年，北越军队和越共在越南人民的节日农历新年发动大规模的突袭攻势，进攻南越三十六个主要城镇，标示着战争的转折点。在美国，很多人在道义上反对参战。詹森总统将政策转为逐步降级，在巴黎开始和平谈判。1969～1973年美国自越南撤军，但在1970年战争向柬埔寨和寮国扩大。到1971年和谈继续陷於僵局。1973年恢复和谈，协定实施停火，尽管有停战协议，战斗仍继续不断，互相指责对方多次破坏停火。1975年北越军队相信，对南方的全面进攻现已切实可行。同年4月南越投降。1976年全国正式统一为越国社会主义共和国。超过200万人（包括58,000名美国人）在战争中丧生，其中一半是平民。
English version：
1955～1975年
Vietnam War
Protracted effort by South Vietnam and the U.S. to prevent North and South Vietnam from being united under communist leadership. After the First Indochina War, Vietnam was partitioned to separate the warring parties until free elections could be held in 1956. Ho Chi Minh's popular Viet Minh party from the north was expected to win the elections, which the leader in the south, Ngo Dinh Diem, refused to hold. In the war that ensued, fighters trained in the north (the Viet Cong) fought a guerrilla war against U.S.-supported South Vietnamese forces. At the height of U.S. involvement, there were more than half a million U.S. military personnel in Vietnam. The Tet Offensive of 1968, in which the Viet Cong attacked 36 major South Vietnamese cities and towns, marked a turning point in the war. Many in the U.S. had come to oppose the war on moral and practical grounds, and Pres. Lyndon B. Johnson decided to shift to a policy of “de-escalation.” Peace talks were begun in Paris. Between 1969 and 1973 U.S. troops were withdrawn from Vietnam, but the war was expanded to Cambodia and Laos in 1970. Peace talks, which had reached a stalemate in 1971, started again in 1973, producing a cease-fire agreement. Fighting continued, and both sides denounced the other for numerous truce violations. In 1975 the North Vietnamese became convinced that a full-scale invasion of the south was possible. The south surrendered later that year, and in 1976 the country was reunited as the Socialist Republic of Vietnam. More than 2 million people (including 58,000 Americans) died over the course of the war, half of them civilians.