An AH Cliché. Based around the idea that if a country/religion/ideology etc loses territory somewhere as a result of a change, it has to gain territory elsewhere to compensate. The most common example is the USA losing the Civil War (and therefore the CSA breaking off as a separate country) only for the USA to compensate by conquering parts of Canada.
Another common example is that if the Byzantine Empire survives (so Anatolia is Christian) then Muslim Spain (Al-Andalus) will also survive so Islam gets compensated.
This daft idea is known to be a berserk button for Glen, who once made a sarcastic map playing on the cliché. In it, Quebec votes for independence from Canada in 1995 and Canada reacts by successfully conquering the Pacific Northwest and New England from the USA.