Complex sentence: In March 1951, at the Battle of Mao Khe near the port of Haiphong, de Lattre again defeated Giap, who had underestimated de Lattre's army's ability to deploy naval guns and to move reinforcements aboard assault boats on deep estuaries and canals.
Split into simpler sentences: In March 1951, at the Battle of Mao Khe near the port of Haiphong, de Lattre again defeated Giap. This time, Giap underestimated de Lattre's army's ability to deploy naval guns and move reinforcements aboard assault boats on deep estuaries and canals.