How did Klemens von Metternich limit Prussia’s plans to annex Saxony?

At the Congress of Vienna, Klemens von Metternich sought to maintain a balance of power in Europe and specifically opposed the territorial expansion of Prussia, including its designs to annex the entire Kingdom of Saxony.1

To limit these plans, Metternich utilized the following diplomatic strategies:

• Building a Common Front: Metternich successfully created a coalition with Great Britain and France to oppose the territorial ambitions of Prussia and Russia. This alliance was so significant that the three powers even concluded a secret treaty of defensive alliance in January 1815 to counter Prussian and Russian claims.12
• Diplomatic Pressure: By leveraging his role as a leader of the congress and maintaining close ties with the British foreign secretary, Robert Stewart, Viscount Castlereagh, Metternich was able to exert pressure that resulted in a reduction of Prussian demands on Saxony.1

Ultimately, these efforts prevented the total annexation of Saxony. Instead, Prussia received only two-fifths of the kingdom, with the remainder preserved as a truncated state.23