 Complete the following phrase:  As Austria, France and Russia formed a new anti-Prussian coalition, Frederick became convinced that Prussia would be attacked in early 1757 and once again chose to strike first. On 29 August 1756 he preemptively invaded neighbouring Saxony, beginning the Third Silesian War. As Austrias and Prussias allies joined the fighting, the conflict quickly widened into what became the pan-European Seven Years War. The Prussians occupied Saxony in late 1756 and made large advances in Bohemia in early 1757, winning a series of battles while advancing to Prague. In May Prussian forces drove back the Austrian defenders in the Battle of Prague, taking great losses, and then besieged the city. An Austrian counter-attack culminated in the major Austrian victory at the 