The plot is from a novel of Belleforest, copied from one by Bandello (18th vol., vi.). There is a story resembling it in Ariosto's Orlando Furioso, bk. v., another in the Geneura of G. Turberville, and Spenser has a similar one in the Faërie Queene, book ii. canto iv.
Much Ado about Nothing. After a war in Messina, Claudio, Benedick, and some other soldiers went to visit Leonato the governor, when the former fell in love with Hero, the governor's daughter; but Benedick and Beatrice, being great rattle-pates, fell to jesting, and each positively disliked the other. By a slight artifice their hatred was converted into love, and Beatrice was betrothed to the Paduan lord. In regard to Hero, the day of her nuptials was fixed; but Don John, who hated Claudio and Leonato, induced Margaret, the lady's maid, to dress up like her mistress, and to talk familiarly with one Borachio, a servant of Don John's; and while this chit-chat was going on, the Don led Claudio and Leonato to overhear it. Each thought it to be Hero, and when she appeared as a bride next morning at church, they both denounced her as a light woman. The friar, being persuaded that there was some mistake, induced Hero to retire, and gave out that she was dead. Leonato now challenged Claudio for being the cause of Hero's death, and Benedick, urged on by Beatrice, did the same. At this crisis Borachio was arrested, and confessed the trick; Don John fled, the mystery was duly cleared up, and the two lords married the two ladies.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894