Complex sentence: In November 1940, the British and Commonwealth forces gained an intelligence advantage when the government code and cypher school at Bletchley Park broke the high grade cypher of the Italian Royal Army ("Regio Esercito") in East Africa.
Split into simpler sentences: In November 1940, the British and Commonwealth forces received an intelligence advantage. The government code and cypher school at Bletchley Park broke the high grade cypher of the Italian Royal Army ("Regio Esercito") in East Africa.