Yeah, it looks like he went through some pretty bad stuff. Sadly many great writers are that way as the result of great trauma or personal demons:
On November 1944, his division first saw combat, landing in the Philippines. The 11th Airborne Division was not used as paratroopers, however, but as light infantry during the Battle of Leyte. The division helped secure the area after the five divisions that had gone ashore earlier.[2]: 43
For a variety of reasons, Serling was transferred to the 511th's demolition platoon, nicknamed "The Death Squad" for its high casualty rate. According to Sergeant Frank Lewis, leader of the demolitions squad, "He screwed up somewhere along the line. Apparently he got on someone's nerves."[2]: 45 Lewis also judged that Serling was not suited to be a field soldier: "he didn't have the wits or aggressiveness required for combat."[2]: 45 At one point, Lewis, Serling, and others were in a firefight, trapped in a foxhole. As they waited for darkness, Lewis noticed that Serling had not reloaded any of his extra magazines. Serling sometimes went exploring on his own, against orders, and got lost.[2]: 45
Serling's time in Leyte shaped his writing and political views for the rest of his life. He saw death every day while in the Philippines, at the hands of his enemies and his allies, and through freak accidents such as that which killed another Jewish private, Melvin Levy. Levy was delivering a comic monologue for the platoon as they rested under a palm tree when a food crate was dropped from a plane above, decapitating him. Serling led the funeral services for Levy and placed a Star of David over his grave.[2]: 45 Serling later set several of his scripts in the Philippines and used the unpredictability of death as a theme in much of his writing.[2]: 46 In the 1960 Twilight Zone episode "The Purple Testament", a prologue written by Serling stated, "Infantry platoon, U.S. Army, Philippine Islands, 1945. These are the faces of the young men who fight, as if some omniscient painter had mixed a tube of oils that were at one time earth brown, dust gray, blood red, beard black, and fear—yellow white, and these men were the models. For this is the province of combat, and these are the faces of war."
Serling returned from the successful mission in Leyte with two wounds, including one to his kneecap,[2]: 47 but neither kept him from combat when General Douglas MacArthur deployed the paratroopers for their usual purpose on February 3, 1945. Colonel Haugen led the 511th Parachute Infantry Regiment as it landed on Tagaytay Ridge, met the 188th Glider Infantry Regiment and marched into Manila. It met minimal resistance until it reached the city, where Vice Admiral Sanji Iwabuchi had arranged his 17,000 troops behind a maze of traps and guns and ordered them to fight to the death.[2]: 47–49 During the next month, Serling's unit battled block by block for control of Manila.
When portions of the city were taken from Japanese control, local civilians sometimes showed their gratitude by throwing parties and hosting banquets. During one of these parties, Serling and his comrades were fired upon, resulting in many soldier and civilian deaths. Serling, still a private after three years, caught the attention of Sergeant Lewis when he ran into the line of fire to rescue a performer who had been on stage when the artillery started firing.[2]: 49
As it moved in on Iwabuchi's stronghold, Serling's regiment had a 50% casualty rate, with over 400 men killed or wounded. Serling was wounded and three comrades were killed by shrapnel from rounds fired at his roving demolition team by an antiaircraft gun.[2]: 50 He was sent to New Guinea to recover but soon returned to Manila to finish "cleaning up".
Serling's final assignment was as part of the occupation force in Japan.[2]: 51 During his military service, Private Serling was awarded the Purple Heart, the Bronze Star,[10] and the Philippine Liberation Medal.[4][11]
Serling's combat experience affected him deeply and influenced much of his writing. It left him with nightmares and flashbacks for the rest of his life.[4] He said, "I was bitter about everything and at loose ends when I got out of the service. I think I turned to writing to get it off my chest."[3]