Why did austria shift alliances in the mid-1700s?

An alliance between Austria and France was made in 1756 following the First Treaty of Versailles. Prior to this, they had been enemies for at least a couple hundred years (wars were fought). France and its allies were winning over Austria, causing Austria to lose territory. During the "War of the Austrian Succession" France and Prussia attacked Austria, and Austria again lost territory. At this time Austria was allied with Britain, but Britain didn't help them much, so Austria started to evaluate its ties with Britain. The ruler of Austria at the time, Maria Theresa, made it her priority to establish better allies. The alliance ended during the French Revolution.

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