January 25, 1866 the British Empire declares war on the United States of America to create a second front in support of the Confederate States of America. In February a fleet of British ships begins to blockade the United States. The United States sends a squadron to break the blockade but they are ships defeated of the coast of New England and the blockade of Boston, New York and the Chesapeake continues.
As part of the armistice and Treaty of New Brunswick the Union made Nebraska the 24th state, and ceded the Puget Sound region and other British occupied territory (Michigan) to the British Dominion of Canada.
The Union calls this war "The Second British War" and the British call it "The American War."