Chapter One: Why Yossarian’s censorship of the letters is an example of this kind of irony.

Yossarian maintains a daily fever of 101 and is very happy having all his meals served in bed. He plans to remain sick until the end of the war. Yossarian writes everyone he knows, saying that he is going on a dangerous mission and will write back when he returns. His only work is to censor the letters of the other patients. This is ironic because Yossarian, a liar and manipulator, is charged with upholding military standards.