Complex sentence: In the afternoon, the 1st SS and 116th Panzer Divisions made renewed attacks, but the flanks of the Mortain positions had been sealed off, allowing the American VII Corps to contain the German advance.
Split into simpler sentences: In the afternoon, the 1st SS and 116th Panzer Divisions attacked American forces. However, the flanks of the Mortain positions had been sealed off, allowing the American VII Corps to contain the German advance.