Complex sentence: Gentile returns to the United States after several months in Sicily, his allies Mauro and Valenti are gunned down by Masseria forces in 1920 and 1922 ending the conflict and making Joe Masseria one of the top mafia Bosses in New York.
Split into simpler sentences: Gentile returns to the United States after several months in Sicily. His allies Mauro and Valenti are gunned down by Masseria forces in 1920 and 1922 ending the conflict and making Joe Masseria one of the top mafia bosses in New York.