Perpetual Peace: A Philosophical Essay (1917 ed.)
During the wars of the French Revolution Kant was inspired by the Treaty of Basel to contemplate how both self-interest and international cooperation might bring an end to war. This edition is interesting because it was published during World War One.
Perpetual Peace: A Philosophical Essay, translated with Introduction and Notes by M. Campbell Smith, with a Preface by L. Latta (London: George Allen and Unwin, 1917).
The text is in the public domain.