The Oregon Treaty, signed on 15 June 1846 between Britain and the US, describes the boundary between BNA and the US west of the Rocky (or Stony) Mountains. A compromise between the American desire for a boundary with Russian Alaska at 54°40½ N lat to the Columbia River mouth, the treaty set the boundary at 49° to the middle of the channel between the mainland and Vancouver Island, thence through the middle of the channel and Juan de Fuca Strait to the Pacific. But the "middle of the channel" could have followed either Rosario Strait or Haro Strait between the Strait of Georgia and Juan de Fuca Strait and and between them lay San Juan Island which was claimed by both Britain and the US. The Americans landed troops on the island in 1859. The boundary through the strait thus remained in doubt until 1872, when it was referred to the German emperor, Wilhelm I, for arbitration. The settlement favoured the US claim, ie, Haro Strait.