Why did Austria reverse its alliance with Britain and join France in 1756?

The shift in alliances in 1756, known as the Diplomatic Revolution, occurred because the traditional Anglo-Austrian partnership had become increasingly ineffective and unsatisfactory for both parties following the War of the Austrian Succession.1

Austria’s primary objective was the recovery of Silesia from Prussia, but the British were unwilling to provide the level of military support required to achieve this goal. Conversely, the British felt that their subsidies to Austria had yielded little benefit.231

The alliance finally collapsed due to the Convention of Westminster (January 1756), in which Britain and Prussia agreed to defend each other's territories in Germany. This agreement signaled to Wenzel Anton von Kaunitz, Maria Theresa’s chancellor, that the British alliance was no longer worthwhile. Fearing isolation, Austria sought a rapprochement with France, leading to the First Treaty of Versailles in May 1756, which established a defensive alliance between the two former rivals.2