In great depth, Volume II examines the escalation of the Vietnam War and its development into a violent stalemate, beginning with the overthrow of the Ngô Đình Diệm in 1963 to the aftermath of the 1968 Tết Offensive. This five-year period was, for the most part, the fulcrum of a three-decades-long struggle to determine the future of Vietnam and was marked by rival spirals of escalation generated by the Democratic Republic of Vietnam and the United States. The volume explores the war's military aspects on all sides, the politics of war in the two Vietnams and the United States, and the war's international and transnational dimensions in politics, protest, diplomacy, and economics, while also paying close attention to the agency of historical actors on both sides of the conflict in South Vietnam. Sheds light on the escalation of the Vietnam War between 1963 and 1968 and its development into a violent stalemate. Lien-Hang T. Nguyen holds the Dorothy Borg Chair in the History of the United States and East Asia at Columbia University. She is the author of Hanoi's War: An International History of the War for Peace (2012), which won prizes from the Society for Historians of American Foreign Relations and the Society for Military History. She is the co-founder of Vietnamese Studies at Columbia and serves on the Board of Trustees of Fulbright University Vietnam. Andrew Preston is Professor of American History at Clare College, University of Cambridge. A specialist in the history of US foreign relations, he is the author or editor of nine books, including American Foreign Relations: A Very Short Introduction (2019) and Sword of the Spirit, Shield of Faith: Religion in American War and Diplomacy (2012). In 2020–21, he was President of the Society for Historians of American Foreign Relations (SHAFR).