 Complete the following phrase:  On 29 September the Austrians attacked Fredericks camp in Bohemia, resulting in a Prussian victory at the Battle of Soor, despite the Austrian surprise and superior numbers. Soon low supplies forced the Prussians to withdraw into Upper Silesia for the winter. In November Austria and Saxony prepared a surprise double invasion of Brandenburg, hoping to seize Berlin and end the war outright. On 23 November Frederick surprised the Austrian invaders in the 