Complex sentence: The PRC had sent some of its best units to join the war and had anticipated a relatively quick and easy victory, due to a common feeling within the Chinese leadership that their army's' superior' military doctrine would overcome their material and technological inadequacies.
Split into simpler sentences: The PRC had sent some of its best units to join the war and had anticipated a relatively quick and easy victory. Due to a common feeling within the Chinese leadership that their army's' superior' military doctrine would overcome their material and technological inadequacies.