In 1947 when the US flag flew from the Tower of London, I dare say I thought this here British Empire was toast! Fortunately for me, the United States wasn't counting on Canada.
With all of the US forces in Europe, or the Pacific, they had no-one defending the 48 contiguous states! Our sexy Canadian forces rolled into New England around '46 and captured New York on the same day London fell. The US threatened nukes of course, but it's not like it would change anything when the British High Command was already making itself at home in Boston.
Golly gee, it took a few years before the Isles were resecured with Soviet and French help, but we did it. In the end, New England - that is, Maine, Vermont, New Hampshire, Connecticut, Rhode Island, and Massachusetts - and Alaska wave the Royal Union Flag these days.
God, how I love karma. Truman was livid, chaps! But hey, that's what he gets for invading Britain and her other bits and pieces.