Complex sentence: After the Korsun airfield was abandoned on 12 February, deliveries were parachuted, and fuel drums and ammunition crates were dropped into snowbanks by the transports flying just above the deck.
Split into simpler sentences: After the Korsun airfield was abandoned on 12 February, deliveries had to be dropped in by parachute. Fuel drums and ammunition crates were dropped into snowbanks by transports flying just above the deck.