Simplify the following text for a Grade 8 native English-speaking person.
Original: On 14 October 1806 , at the Battle of Jena-Auerst Ã dt , the French defeated the Prussian army led by Frederick William , and the Prussian army collapsed .
Simplified: On 14 October 1806 , at the Battle of Jena-Auerst Ã dt , the French defeated the Prussian army , and it collapsed .