Complex sentence: Twelve Hurricanes were flown off "Argus" to reinforce Malta (Operation "White"), but the threat of the Italian fleet prompted a premature fly-off from "Argus" and its return to Gibraltar.
Split into simpler sentences: Twelve Hurricanes were flown off "Argus" to reinforce Malta (Operation "White"). But the threat of the Italian fleet prompted a premature fly-off from "Argus" and its return to Gibraltar.