Complex sentence: On 25 September, the German reinforcements attacked, crossed the Somme south of Péronne and then advanced to take a bridge between Hem and Feuillères, when a French attack north of the Somme against the II Bavarian Corps forced a hurried withdrawal.
Split into simpler sentences: On 25 September, the German reinforcements attacked, crossed the Somme south of Péronne and then advanced to take a bridge between Hem and Feuillères. A French attack north of the Somme against the II Bavarian Corps, forced a hurried withdrawal.