“My step-grandfather, Boyd Sullivan of Mississippi fought with Pershing both in Mexico and in WWI.”
so did my father...but he never opened his mouth about it...
he spoke more about Pancho Villa which they all found frustrating because they really wanted him...
Boyd had been born into the Sullivan’s Hollow clan in Mize Mississippi son of Wild Bill Sullivan and had been forced to leave early on as a lad when he shot a constable by the train depot in an argument over a woman. he went and joined up with Pershing which was easy since he had horsing skills. He spoke at length about this.
WWI, he recounted the voyage and the countryside and the French(?) women but said the fighting was like horror punctuated by boring horrible conditions and illness. He was glad when it was over and wondered aloud why he’d gone in the first place. He died in 1980 in his mid 80s.
My maternal great uncle RE Horne likewise of MS fought in WWI as well and was gassed and badly damaged. He suffered from shell shock all his life and drank like a fish. He died when I was a toddler and I remember being held by him as he was dying in his late 50s at the Veterans Hospital in Biloxi in barracks style wards. He had a hard life...some was the war, some was his personality and his reaction to the war.
Everyone is different in how they handle that sort of stress.