Pig War: A pig and an international boundary dispute

English Camp Blockhouse on San Juan IslandWashington State Archives' Digital ArchivesState Library Photograph Collection, 1851-1990. 1955.


In 1846, the United States and Great Britain signed the Oregon Treaty, establishing the northwest boundary between the United States and the British colony of Canada. The San Juan Islands in the Haro Strait, however, was not described accurately in the treaty and became a point of contention between the two nations, which had already settled and claimed the area.


In 1859, an American farmer shot a pig owned by a British citizen for uprooting his potatoes. The British authorities threatened to arrest the American, who promptly petitioned for U.S. troops to intervene. British warships sailed into the harbor. An international incident resulting from this conflict came to be known as the “Pig War.”


Start with secondary sources 

Use secondary sources to gain basic knowledge of your topic, its significance, and historical context.

Ask a Librarian online at Washington State Library to get expert help in locating useful secondary sources. 


Then use primary sources

Use primary sources to deepen your understanding of the topic, and assemble evidence to support your own analysis and interpretation.

Ask an Archivist online at Washington State Archives to get expert help in locating useful primary sources.


Some key historical research questions:

  • What reasoning did each of the governments use to establish their claim of ownership of the Islands?
  • Why did the United States want to claim these Islands?
  • Have other more serious conflicts been started by seemingly minor events?
  • Did similarities and differences between British and American culture have any influence on the conflict or its resolution?
  • How violent was the “Pig War”?
  • How long did it last?
  • What methods were used to resolve the conflict?
  • Were the tactics used by the British and Americans necessary, appropriate, or successful?
  • Who were Lyman Cutler, Charles Griffin, William Pickering, William Harney, George Pickett, James Douglas, and Winfield Scott, and what roles did they play?
  • How was the Hudson’s Bay Company formed, and why was it important to the British Government?
  • Consider other possibilities for historical questions as you analyze and interpret this topic.


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