This monograph considers the role of international law in Singapore’s early years from colony to independent state against the political and historical backdrop of Southeast Asia in the highly volatile 1960s. It can be broadly divided into three main parts. Part I describes Singapore’s international legal personality during its colonial period (1819–1963). Part II details the difficulties Singapore experienced in its attempt to free itself from colonial rule by becoming a constituent state of the Federation of Malaysia in 1963. Opposition to the formation of Malaysia from its two largest neighbours—the Philippines and Indonesia—threatened to derail the formation of Southeast Asia’s first and only federation and to deny Singapore its independence. The period discussed in this Part runs from 1963 to 1965. Part III deals with the international law issues that Singapore had to deal with after it became independent in 1965. A large portion of this monograph is devoted to discussing the various problems and issues Singapore confronted between 1965 and 1970.