
Iago then uses Desdemona's requests that he be merciful to Cassio to make Othello suspect that Desdemona is cheating on him with Cassio. Meanwhile, Iago convinces Desdemona to try to get Othello to reinstate Cassio. He then goads Roderigo into provoking Cassio, starting a brawl. That night, while Othello and Desdemona go to bed to consummate their marriage, Iago succeeds in getting Cassio drunk. Iago quickly hatches a plan to make Othello believe that Desdemona has been unfaithful to him with either Cassio or Roderigo. When the Venetians arrive in Cyprus, the governor Montano reports that a storm at sea has drowned the Turkish fleet, eliminating the military threat. Iago reassures Roderigo that he will still win Desdemona in the end, then privately admits that he's just using Roderigo for money while he plots his own revenge. The Duke then sends Othello to lead a fleet of Venetians to defend Cyprus from a Turkish attack. Brabantio grudgingly blesses the newlyweds. When summoned, Desdemona supports Othello's story.

Othello responds that it was stories of his exciting life history and military bravery that won Desdemona. In front of the Duke, Brabantio accuses Othello of having used magic to seduce Desdemona. Brabantio, enraged, interrupts Othello as he receives an urgent message from the Duke of Venice, and accompanies Othello see the Duke. The two men go to the home of Desdemona's father, the senator Brabantio, and rouse him with graphic descriptions of his daughter having sex with the Moor.

Iago responds that he too hates Othello, for whom he works as a standard-bearer: Othello chose Cassio, rather than Iago, to be his lieutenant. In Venice, Roderigo complains to Iago that, despite the money he's given Iago to help him woo Desdemona, she's eloped with the Moorish general Othello.
