Complex sentence: While heading back to Silesia, Frederick learned of the fall of Breslau (22 November); he and his men covered in 12 days and, at Liegnitz, joined up with the Prussian troops who had survived the fighting at Breslau.
Split into simpler sentences: While heading back to Silesia, Frederick learned of the fall of Breslau (22 November). He and his men covered in 12 days and, at Liegnitz, joined up with the Prussian troops who had survived the fighting at Breslau.