Complex sentence: The Imperial Japanese Navy had developed a seaplane base on Parry Island and following its capture on 22 February Seebees from the 110th Naval Construction Battalion expanded the existing base building a coral-surfaced parking area and shops for minor aircraft and engine overhaul.
Split into simpler sentences: The Imperial Japanese Navy had developed a seaplane base on Parry Island. Following its capture on 22 February, Seebees from the 110th Naval Construction Battalion expanded the base, building a coral-surfaced parking area and shops for minor aircraft and engine overhaul.