Besides the convenience of such an understanding on the part of the two great commercial countries, from which language, personal appearance, and manners render mutual escape so easy, the condition of the frontier of the United States and Canada was such as to make this provision all but necessary for the preservation of the peace of the two countries. An extensive secret organization existed in the border States, the object of which was, under the delusive name of "sympathy," to foment and aid rebellion in the British Provinces. Although an agreement for mutual extradition of necessity left untouched a great deal of political agitation unfriendly to border peace, murder and arson were, of course, within its provisions. It appears from the testimony of the parties best informed on the subject, that the happiest consequences flowed from this article of the treaty of Washington. No more was heard of border forays, "Hunters' Lodges," "Associations for the Liberty of Canada," or violences offered or retaliated across the line. The mild, but certain influence of law imposed a restraint, which even costly and formidable military means had not been found entirely adequate to produce. The stipulations for extradition in the treaty of Washington appear to have served as a model for those since entered into between the most considerable European powers. A convention for the same purpose was concluded between England and France on the 13th of February, 1843, and other similar compacts have still more recently been negotiated. Between the United States and Great Britain the operation of this part of the treaty has, in all ordinary cases, been entirely satisfactory. Persons charged with the crimes to which its provisions extend have been mutually surrendered; and the cause of public justice, and in many cases important private interests, have been materially served on both sides of the water.