Iago wanted Cassio to drink more wine because he wanted Cassio to be drunk and argumentative when Roderigo would approach him later that night. Iago told Montano that Cassio was drunk every night. He wanted to cast doubt on Othello's judgment for appointing Cassio, by implying that Cassio may be drunk during battle. This led to Othello stripping Cassio of his position. Othello thought that Cassio was irresponsible and dishonourable.
Iago wanted Cassio to drink more wine because he wanted Cassio to be drunk and argumentative when Roderigo would approach him later that night. Iago told Montano that Cassio was drunk every night. He wanted to cast doubt on Othello's judgment for appointing Cassio, by implying that Cassio may be drunk during battle. This led to Othello stripping Cassio of his position. Othello thought that Cassio was irresponsible and dishonourable.
So that Cassio gets uncontrollable and starts a fighht with Roderigo.
Because Iago knows that Cassio cannot handle his liquor and will be more likely to fight if he's drunk and that will make him look worse in Othello's eyes.
to make cassio mad to he can get in a fight with him because cassio has a hot temper so iago tell this to roderigo to Othello could release Cassio of his position as lieutenant . Iago gets Cassio drunk in the night so after he is drunk Roderigo comes out and makes Cassio angry again so they get in a fight during they fighting some one goes and ring the bell to Othello could be awerd so Otello comes out of his room and he ask whtas going on so Montano tells him and Othello said that even thouhg as much he loves him he has to discharged him out of his position of lieutenant .
Primarily the fact that Iago has suggested to him that that is what is being talked about. By this point, Iago has got Othello into such a state he cannot interpret anything Cassio or Desdemona does as being innocent.
Bianca
Othello commits suicide. Iago is sentenced to torture. Cassio becomes governor of Cyprus.
Iago had lied to Othello and convinced him that Desdemona was secretly having sex with Cassio.
He told Montano that Cassio was drunk every night. He also casted doubt on Othello's judgment for appointing Cassio, who might be drunk in a moment of crisis.
Cassio has no head for liquor; it doesn't take much to get him drunk. He knows it and Iago knows it too. Nevertheless Iago is able to persuade him to drink more than he ought.
Iago feels that Cassio's promotion should have gone to him. He envies Cassio.
Iago says that he was sleeping next to Cassio and that Cassio was having a dream about making love to Desdemona.
In Act II Scene 3, Iago knows that Cassio's weakness is unable to tolerate alcohol therefore he targets this weakness and persuades Cassio to drink with him. At first Cassio said no to Iago's offer because he was assigned to be on duty at night however, he ends up drinking anyways because of Iago's persistent persuasion. Iago's plan was slowly progressing. After a great amount of alcohol consumption, Cassio became drunk and went to the washroom by himself. While he was doing his business, an unknown man which was Roderigo disguised with a beard, pushed him from behind. This action angers Cassio therefore he chases the "unknown man". At the same time, Iago was talking to Montano about Cassio's drinking problem. Cassio runs into Iago and Montano, a fight occurs and Montano gets injured as Iago stabs him without anyone else noticing. The fight causes Othello to appear and strips Cassio of his rank because "he" injured Montano.
Iago advises Cassio to ask Desdemona to plead on his behalf. This will help Iago poison Othello's mind, as Desdemona will appear to be doing so out of her (illicit) love for Cassio.
Iago's plan is to make Cassio drunk and get him into a brawl that will ruin Cassio's reputation and cause him to lose his position. He urges Roderigo to provoke Cassio "to put our Cassio in some action/ that may offend the isle." As usual,Roderigo is duped by Iago's manipulative words and agrees to do this, even though all he ends up with is a sound beating from Cassio. Iago, however, succeeds in getting Cassio dismissed from his lieutenancy to Othello, which plays in toIago's master plan to ruin Othello.
Iago gets Cassio drunk. Cassio does not have a head for liquor and he knows it and he tells Iago he's had enough, but Iago makes himself extremely persuasive, using the same kind of arguments people still use to make people drink more than they should. "O! they are our friends; but one cup; I'll drink for you" and "What, man! "tis a night of revels; the gallants desire it." In other words, "Don't let our friends down, just have one more, it's a party! don't be a wet blanket." Iago knows, as Cassio does, that Cassio is at the point where he will start to get drunk and quarrelsome, and will start a fight with someone, when he's supposed to be on duty.
Iago does the plotting alone; Roderigo is his dupe and has no more idea how he is being used than Cassio does. In Act II Scene 3 Iago makes sure both are drunk and quarrelsome and then eggs Roderigo on so Cassio will fight with him, thus ensuring Cassio's dismissal. In Act IV Scene 2 Iago lies to Roderigo, telling him that Othello is being sent to Mauretania where Roderigo will never have a chance to see Desdemona. Iago tells him that this is only possible because there is a competent replacement for Othello on hand in Cyprus in the person of Cassio. Get rid of Cassio, and Othello must stay in Cyprus. In this way Iago dupes Roderigo into trying to murder Cassio in Act V.
Othello was just out of earshot when Iago talks to Cassio. He has told Othello that he is talking to Cassio about Desdemona but he is really talking about the woman that Cassio is really having an affair with, Bianca. In 'Othello' Iago tricks Othello by planting Desdemona's handkerchief in Cassio's room.
Iago has been passed over for a promotion. Cassio got the promotion to Lieutenant even though Iago had more time in service as a soldier. Cassio got the promotion over Iago because his learning included theory and strategy whereas Iago's did not.
By suggesting it as a possibility, then discounting it. He thus forced Othello to push for some evidence proving it. By using the con artist's technique of the stall, together with his reputation of honesty, Iago makes Othello think that Iago could not have made the suggestion unless there was some reason for it, and the more Iago denies that there is such a reason, the more Othello believes it.