Complex sentence: The invasion reached a peak, when on December 31,1775, the Continental Army, under the command of General Richard Montgomery was defeated before the gates of the city of Quebec, resulting in the death of Montgomery and the capture of over 400 men.
Split into simpler sentences: The invasion reached a peak on December 31,1775, when the Continental Army, under the command of General Richard Montgomery, was defeated before the gates of the city of Quebec. The battle resulted in the death of Montgomery and the capture of over 400 men.