The Law of Nations (1833 ed.)
An influential English translation of a work which had a profound impact on the ideas of the American founders. Chitty brought it to the attention of 19th century English readers and it was brought up to date with additional notes by Ingraham in the 1850s.
The Law of Nations; or, Principles of the Law of Nature, applied to the Conduct and Affairs of Nations and Sovereigns. From the French of Monsieur de Vattel. From the New Edition by Joseph Chitty, with additional notes and references by Edward D. Ingraham (Philadelphia: T. & J.W. Johnson & C., 1883).
The text is in the public domain.