War is used metaphorically in Act 3, Scene 3 when Othello becomes convinced that Desdemona is cheating on him:
. . .Ho, now forever
Farewell the tranquil mind! Farewell content!
Farewell the plumed troop and the big wars
That make ambition virtue! Oh farewell,
Farewell the neighing steed and the shrill trump
The spirit-stirring drum, the ear-piercing fife,
The royal banner, and all quality,
Pride, pomp, and circumstance of glorious war!
The quotation shows that once Othello believes he has lost Desdemona, he feels that everything that has given his life meaning is also gone:
Othello's occupation's gone!
We see that Othello is first and foremost a soldier, and many of his decisions regarding Desdemona are based on that background.