The 1846 Oregon Treaty forced by President Polk established the 49th parallel as the boundary between Canada and the U.S., except in the San Juan archipelago. While both sides agreed that all of Vancouver Island would remain British, the treaty wording was left vague enough as to put the boundary between modern-day Gulf Islands and San Juan Islands in dispute. Conflicts over this border led to the Pig War in 1859. Skirmishes continued until the boundary issue was eventually placed in the hands of Kaiser Wilhelm I of Germany for arbitration. The border was finally established in 1872.