Who promoted Cassio to the post of lieutenant and what was its result?

Answer: In the tragedy Othello by Shakespeare, Othello promoted Cassio to the post of lieutenant because he was very close friend of Othello and helped Othello and his beloved Desdemona in their love affair.

This incident brought a dramatic turn in the play. Another character of the play Iago was senior to Cassio and more experienced than Cassio in technique of warfare. So, Iago deserved the post of lieutenant. He was not happy with Othello’s decision to promote Cassio. Besides, Cassio’s characteristics of impressing others and speaking very sweetly made Iago jealously. He planned to ruin both Othello and Cassio by treachery and making them enemy of each other. At the end of the play, it was seen that the protagonist killed himself after murdering his wife Desdemona on the doubt of extramarital affair with Cassio. Thus, Iago took revenge.