This is the thesis of Dr. Hans Bartenstein from Zurich, Switzerland. On the basis of this thesis the University of Zurich awarded him a doctor's degree in law in 1980. This thesis investigates the contents of "the agreement on ending war and restoring peace in Vietnam" signed in early 1973 in Paris. Upon signature of the agreement US armed forces and its allies withdrew from Vietnam. The agreement was never implemented as far as a political solution of the conflict in Vietnam was concerned. In 1975 the armed forces of North Vietnam invaded the south of the country, thereafter Vietnam was unified under the leadership of the communist North Vietnamese government. The agreement provided for an end of the hostilities on the entire territory of Vietnam and subsequent free and democratic elections in South Vietnam under international supervision. Such elections never took place. This thesis describes the history of US involvement in Vietnam, the negotiations leading to the signature of the agreement and details its contents. It investigates the various ways to end an armed conflict provided by international law. It also investigates the contents of the agreement concerning the international humanitarian law applicable in the Vietnam war.