In 1756, Frederick attempted to forestall Britain's financing of a Russian army on Prussia's border by negotiating an alliance with England at the Convention of Westminster, in which Prussia would protect Hanover against French attack and England would no longer subsidise Russia. This treaty triggered the Diplomatic Revolution in which Habsburg Austria and Bourbon France, who had been traditional enemies, allied together with Russia to defeat the Anglo-Prussian coalition. To strengthen his strategic position against this coalition,on 29 August 1756, Frederick's well-prepared army preemptively invaded Saxony. His invasion triggered the Third Silesian War and the larger Seven Years' War, both of which lasted until 1763. Frederick quickly captured Dresden, besieged the trapped Saxon army in Pirna, and continued marching the remainder of his army toward North Bohemia, intending to winter there. At the Battle of Lobositz Frederick claimed a close victory against an Austrian army that was aiming to relieve Pirna, but afterward withdrew his forces back to Saxony for the winter. When the Saxon forces in Pirna finally capitulated in October 1756, Frederick forcibly incorporated them into his own army. This action, along with his initial invasion of neutral Saxony brought Frederick widespread international criticism; but the conquest of Saxony also provided Frederick with significant financial, military, and strategic assets that helped him sustain the war.