Lawrence's PTSD

Summary
Lawrence was a former soldier in the Vietnam War which causes most of his personality and morals.

My Lai Massacre
Lawrence describes in detail during the story about how when he was in his early twenties he was forced to interrogate a vietnamese soldier who was just a few years younger than him. The Vietnamese Man was often beaten and brutally interrogated, to the point where he could barely even muster a word, and Lawrence was often forced to take part in this beatings. Eventually he couldn't take it anymore, and gave the Vietnamese Man a knife to cut himself loose and defend against the Americans once he broke out of his capitivity.

However, the next morning Lawrence found out that the man had commited suicide rather than try to escape. From then on, multiple time he would find the captured Vietnamese soldiers who were beaten mercilessly, begging for death, and Lawrence would give them merciful killings which formed his philosophy of the Rot and people dying painfully. This philosophy is why it took him so long to end his wife's suffering and that he blames himself for it.