How did Klemens von Metternich use the marriage of Marie-Louise and Napoleon to protect Austria?

Following the oppressive Treaty of Schönbrunn in 1809, Austria was exhausted, debt-ridden, and in urgent need of a respite from French aggression. Klemens von Metternich orchestrated the marriage between the Austrian archduchess Marie-Louise and Napoleon I to exploit the emperor's vanity and secure this necessary relief.1

By facilitating this union, Metternich achieved a relationship between France and Austria that was loose enough to preserve Austria's freedom of action. This strategic move ensured that Austria did not become a client state of the Napoleonic system nor join the Confederation of the Rhine. Consequently, while Austria remained vulnerable, it was no longer the primary target of Napoleon’s hostility, allowing the state time to recover and eventually rearm.1