Complex sentence: The British commanders, led by Montgomery, intended to hold the approximately seven German Panzer Divisions, ontheir front whilst the Americans captured Cherbourg and broke out from the beachhead.
Split into simpler sentences: The British commanders, led by Montgomery, intended to hold the approximately seven German Panzer Divisions, on their front. While the British held the panzers, the Americans captured Cherbourg and broke out from the beachhead.