Why did Austria fail to recover Silesia after the Seven Years’ War?

Austria failed to recover Silesia after the Seven Years’ War primarily because the allied powers—Austria, France, and Russia—were unable to effectively coordinate their combined strength against Prussia. Despite Prussia being heavily outnumbered and facing potential collapse by 1761, Frederick II the Great successfully defended his position through military skill, the exploitation of internal lines, and the efficient use of his state's resources.1

The strategic situation shifted decisively following the death of Empress Elizabeth of Russia in 1762. Her successor, Peter III, withdrew Russia from the conflict, and the subsequent policy under Catherine the Great was to end the war entirely. With Russia out of the fight and France suffering global defeats against Great Britain, Maria Theresa concluded that further military action was untenable. The resulting Treaty of Hubertusburg in 1763 formally acknowledged the status quo ante, leaving Prussia in possession of Silesia.123