Sentence:  Still more jealous bitterness was engendered by the O ' Banion gang 's seizure from a West Side marshalling yard of a freight-car load of Canadian whisky worth $ 100000 and by one of the biggest coups of the Prohibition era - the Sibley warehouse robbery , which became famous for the cool brazenness of the <WSD>operation</WSD> . 
Meaning of the word marked with <WSD> tags:  a planned activity involving many people performing various actions