In the street at night, Iago directs Roderigo to ambush Cassio. When Cassio approaches, Roderigo attacks unsuccessfully and is wounded by Cassio. Iago, from behind, stabs Cassio in the leg and runs away while Cassio cries murder. Othello, hearing Cassio's cry, believes that Iago has done the job he has undertaken. Following Iago's lead, Othello must harden his heart against the charms of his wife and spill her blood in the bed where she has betrayed him.
This scene is framed by Iago's comments on the importance of this night. Before the action starts, he tells Roderigo: "It makes us or it mars us, think of that, / And fix most firm thy resolution" (4-50). To Roderigo, Iago is saying "Be brave, kill Cassio, and you will have Desdemona." To himself, he is saying "Be brave, make sure Roderigo, Cassio, and Desdemona die, and you will have your revenge on Othello."
Roderigo is still wavering, nursing his last flicker of moral sense: "Be near at hand, I may miscarry in't" (6). The comfort of the coward is in belief that someone will protect him, but by agreeing to rely on Iago to make the decisions, Roderigo abdicates responsibility for his own actions and is led out to kill a man he doesn't hate for a cause he no longer thinks can be won.
Iago wastes no emotion on the prospect of Roderigo's death but acknowledges a certain satisfaction when he thinks of Cassio dead. There is the old fury of jealousy against Cassio who has the good opinions of every one, including Othello (until Iago's duplicity, that is). The unfairness of Cassio's happy life rankles Iago as evidenced in his first speech in Act I and continues to frustrate him now: "[I]f Cassio do remain, he has a daily beauty in his life, that makes me ugly" (18-20). Add this to the need to prevent Cassio talking with Othello, and his death will be Iago's pleasure.
Sword fighting is a dangerous business, and certain conventions govern its honorable practice, but there is no honor in this ambush: Roderigo hides himself to strike Cassio; Cassio hits out in the dark in self-defense; and Iago, having promised to back up Roderigo, hunts him down and stabs him. To make an agreement to fight shoulder to shoulder with a comrade and then to step back and stab the man who relied on him is the worst thing a soldier can do. Having now betrayed a value in his profession, Iago exacerbates his infamy.
The cries of the dying men remind Othello of his resolution to kill Desdemona. Again he regrets what he knows he must do. He must force aside, with an iron will, his love for her: "forth of my heart those charms, thine eyes, are blotted, / Thy bed, lust-stain'd, shall with lust's blood be spotted" (34-35). He must close her eyes, stop her looking at him, before he can kill her. Again he stamps out love with overdone violence, conjuring up the image of killing her in her bed, but this mental picture begins to resemble the red and white strawberry-spotted handkerchief, the picture that drives him to madness. The bed in his mind is stained with lust, that is Desdemona's infidelities with Cassio, and will be spotted with "lust's blood" when he kills her in revenge. In that instant, Othello pictures himself killing her with a sword, as Iago will kill Cassio with a sword. Othello will spill her blood on the white sheets, but this time the blood is not from the passion and lust of first love, but from the passion and lust of desperate murder.
The further Iago sinks into villainy, the more Emilia's position has become equivocal. Put on the spot, she automatically backs up her husband, but the circumstances are more and more stretching her loyalty and producing an increasing tension based on her increased knowledge. Sooner or later, Emilia will tell what she knows. For all her words of scorn about husbands, Emilia automatically sides with her husband in what she must know is a scurrilous attack on another woman. She cries "fie upon thee, strumpet!" to which Bianca replies: "I am no strumpet, but of life as honest / As you, that thus abuse me" (120-123). In Bianca's eyes this is true, as all she is doing is standing by her own man, as Emilia is doing with hers.
At this point, Iago feels a certain satisfaction. Roderigo is dead, his money and jewels now securely in Iago's keeping, and no one else is aware of this. Cassio is badly wounded and believes he has been attacked by a gang of thieves. This, for Iago, is a less than perfect result, but Cassio might subsequently die of his injuries or be maimed and crippled, in which case his army career is over. But much is still left to be done before Iago can consider himself safe or triumphant. The night has yet to be accomplished. "This is the night that either makes me, or fordoes me quite" (127-128).
quat (11) a pimple.
bobbed (16) cheated; swindled.
coat (25) a coat of mail worn under outer clothing.
minion (33) mistress; or hussy, as here used.
gastness (106) ghastliness, or terror.
fordoes (129) destroys.