Not necessarily. A few years ago I read an alternate history in which the Confederacy won the American Civil War, with British help. But subsequently the remnant Union allied itself with Germany, which changed the preponderance of forces when World War I came around. Germany destroyed the British Empire. The Union knocked off much of the Confederacy and took over Canada and Russian America (i.e. Alaska). The geography of North America, a sort of walled island continent with a large central river system, tends to favor a large single state.
Why would that help?
The resulting countries could concentrate their energies upon making war on one another.
Not necessarily. A few years ago I read an alternate history in which the Confederacy won the American Civil War, with British help. But subsequently the remnant Union allied itself with Germany, which changed the preponderance of forces when World War I came around. Germany destroyed the British Empire. The Union knocked off much of the Confederacy and took over Canada and Russian America (i.e. Alaska). The geography of North America, a sort of walled island continent with a large central river system, tends to favor a large single state.