Sentence:  To help him on this religious aspect of primitive jazz he had `` Big '' Miller , as a preacher-singer and Hannah Dean , Gospel-singer , while Oscar Brown Jr. , an extremely talented young man , did a slave auctioneer 's call , a field-hands ' work song , and a beautifully sung Negro lullaby , `` Brown Baby '' , which <WSD>was</WSD> one of the truly moving moments of the festival . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)