Austria allied with its traditional rival, France, in the Diplomatic Revolution (1756); Austria, France, and Russia were all aligned against Prussia. Frederick preemptively attacked his enemies with an army of 150,000, beginning the Seven Years' War. The Austrian Army had been reformed by Kaunitz, and the improvements showed in their success over Prussia at Kolin. Frederick achieved one of his greatest victories, however, at Rossbach, where the Prussian cavalry of Friedrich Wilhelm von Seydlitz smashed a larger Franco-Imperial army with minimal casualties, despite being outnumbered two to one. Frederick then rushed eastward to Silesia, where Austria had defeated the Prussian army under the Duke of Bevern. After a series of complicated formations and deployments hidden from the Austrians, the Prussians successfully struck their enemy's flank at Leuthen, with Friedrich once again directing the battle; the Austrian position in the province collapsed, resulting in a Prussian victory even more impressive than the one at Rossbach.