thumb|left|alt=Painting of Frederick marching ahead of Prussian troops with a banner|Frederick the Great at the Battle of Zorndorf by Carl Röchling (1904) In the early spring of 1757, Frederick again invaded Bohemia. He was victorious against the Austrian army at the Battle of Prague on 6 May 1757, but his losses were so great he was unable to take the city, and settled for besieging it. On 18 June 1757, Frederick suffered his first major defeat at the Battle of Kolín, which forced him to abandon his invasion of Bohemia. When the French and the Austrians pursued him into Saxony and Silesia in the fall of 1757, Frederick defeated and repulsed a much larger Franco-Austrian army at the Battle of Rossbach and another Austrian army at the Battle of Leuthen. Frederick hoped these two victories would force Austria to negotiate, but Maria Theresa was determined not to make peace until she had recovered Silesia. Despite its strong performance, the losses suffered from combat, disease and desertion had severely reduced the quality of the Prussian army.
thumb|left|alt=Painting of Frederick marching ahead of Prussian troops with a banner|Frederick the Great at the Battle of Zorndorf by Carl Röchling (1904) In the early spring of 1757, Frederick again invaded Bohemia. He was victorious against the Austrian army at the Battle of Prague on 6 May 1757, but his losses were so great he was unable to take the city, and settled for besieging it. On 18 June 1757, Frederick suffered his first major defeat at the Battle of Kolín, which forced him to abandon his invasion of Bohemia. When the French and the Austrians pursued him into Saxony and Silesia in the fall of 1757, Frederick defeated and repulsed a much larger Franco-Austrian army at the Battle of Rossbach and another Austrian army at the Battle of Leuthen. Frederick hoped these two victories would force Austria to negotiate, but Maria Theresa was determined not to make peace .until she had recovered Silesia. Despite its strong performance, the losses suffered from combat, disease and desertion had severely reduced the quality of the Prussian army