Frank Rinehart of Arizona.
Frank Rinehart was a Libertarian member of the Mexican Senate from the state of Arizona. In 1853, President Hector Niles chose Rinehart to be the chief Mexican negotiator at The Hague for peace talks to end the Rocky Mountain War. Rinehart met with Minister of War John Wolff of the Confederation of North America in June, and the two men arranged to reconstitute an international arbitration panel that had been proposed eight years before, but had never met. The panel was due to meet in November; in the meantime, it was agreed that an armistice between the two nations would go into effect on 1 August, with each army withdrawing ten miles to form a new neutral zone running from the Gulf of Mexico to the border with Russian Alaska.
The arbitration panel produced its report on 15 June 1855, and both Rinehart and Wolff accepted its findings. The two signed the resulting Hague Treaty on 7 August 1855.
Frank Rinehart has no entry in Sobel's index.
Sobel's source for Frank Rinehart's role in ending the Rocky Mountain War is Frank Taft's The End of the War: The Hague in 1853-1855 (Melbourne, 1967).