In order to ensure that Britain retained all of Vancouver Island and the southern Gulf Islands, it was agreed that the border would swing south around that area. Ownership of several channel islands, including the San Juan Islands remained in dispute. The San Juan Islands Pig War (1859) resulted; it lasted until 1872. At that time, arbitration began, with Wilhelm I as head of a three-man arbitration commission. On October 21, 1872, the commission decided in favor of the United States, awarding the San Juan Islands to the U.S.