Complex sentence: In October 1884 a French expeditionary corps of just over 2,000 men captured Keelung, while a simultaneous French operation to capture Tamsui was decisively repulsed by the Chinese.
Split into simpler sentences: In October 1884 they returned with an expeditionary corps of just over 2,000 men. This time they captured Keelung, but a simultaneous French operation to capture Tamsui was decisively repulsed by the Chinese.