Cassio was on duty in the Castle where Othello ruled Cyprus, so Iago decided to make the lieutenant drink too much. He had some difficulty, as Cassio knew that wine soon went to his head, but servants brought wine into the room where Cassio was, and Iago sang a drinking song, and so Cassio lifted a glass too often to the health of the general.
When Cassio was inclined to be quarrelsome, Iago told Roderigo to say something unpleasant to him. Cassio cudgeled Roderigo, who ran into the presence of Montano, the ex-governor. Montano civilly interceded for Roderigo, but received so rude an answer from Cassio that he said, “Come, come, you're drunk!” Cassio then wounded him, and Iago sent Roderigo out to scare the town with a cry of mutiny.
The uproar aroused Othello, who, on learning its cause, said, “Cassio, I love thee, but never more be officer of mine.”
On Cassio and Iago being alone together, the disgraced man moaned about his reputation. Iago said reputation and humbug were the same thing. “O God,” exclaimed Cassio, without heeding him, “that men should put an enemy in their mouths to steal away their brains!”
Iago advised him to beg Desdemona to ask Othello to pardon him. Cassio was pleased with the advice, and next morning made his request to Desdemona in the garden of the castle. She was kindness itself, and said, “Be merry, Cassio, for I would rather die than forsake your cause.”
Cassio at that moment saw Othello advancing with Iago, and retired hurriedly.
Iago said, “I don't like that.”
“What did you say?” asked Othello, who felt that he had meant something unpleasant, but Iago pretended he had said nothing. “Was not that Cassio who went from my wife?” asked Othello, and Iago, who knew that it was Cassio and why it was Cassio, said, “I cannot think it was Cassio who stole away in that guilty manner.”
Desdemona told Othello that it was grief and humility which made Cassio retreat at his approach. She reminded him how Cassio had taken his part when she was still heart-free, and found fault with her Moorish lover. Othello was melted, and said, “I will deny thee nothing,” but Desdemona told him that what she asked was as much for his good as dining.