What is the definition for the phrase "War makes strange bedfellows"

Context: Alliance of USA, Britain, and Soviet Russia during World War II

The phrase "War makes strange bedfellows" can be explained by the uneasy alliance between USA, Britain, and Soviet Russia during World War II

Explanation:

During the second world war, USA was a late entrant, as a country that was pushed into the war despite its isolationist sentiments after the losses of the first world war and great depression.

The other two countries were polar opposites. The Russians were staunch communists by then and Stalin was a full blown dictator akin to Hitler, against whom the alliance was made.

But shared goals made Britain and the USA let go of their ideology and work together with Stalin to defeat the enemy.