My father served in the Third Marine Division during WWII, seeing action at Bougainville, Guam, and Iwo Jima. He almost never talked about his combat experiences, although he would occasionally tell funny stories about non-combat related incidents.
Over the years I have had many people tell me that they thought my father was utterly fearless, how he was able to "keep [his] head when all about him were losing theirs." As for myself, I had never seen him display fear, even in situations where I was scared to death, until an incident which occurred shortly after I graduated from college.
I was visiting my parents and we were watching a documentary on D-Day. As the narrator described the preparations for the landing, Dad became more and more agitated. Dad was upset because they weren't going in at high tide, and more men would be killed because there would be more exposed beach to cross before getting to cover inland. It was obvious that he was distressed by the prospect of soldiers dying on the beaches of Normandy. I wanted to watch the documentary, but I was afraid that the next scenes would be scenes of soldiers being killed as they waded ashore. I suggested that we change the channel.
Later, in the lead up to the ground combat phase of Desert Storm, there were news reports that the Marine Corps was lobbying for an amphibious landing as a part of the invasion. The mere thought of making such a landing appalled my father. He said that if they could find any way to invade Kuwait without making such a landing, they should do so. He was certain that an amphibious assault would result in needless casualties. I tried to reassured him that the technology for such assaults was probably far better than what they had during WWII, but he was adamant. I won't use his exact words, but I got the impression that he thought the Marine Corps brass was "intellectually challenged" for insisting on an amphibious assault.
I only heard my father describe his involvement in an amphibious assault on one occasion. It was his first assault at Bougainville. He said the landing craft operator was too frightened to go all the way up to the beach and dropped the gangplank when they were in about six feet of water. Dad, who was in the front of the landing craft, stepped out and went straight to the bottom, losing his helmet and rifle, and getting trampled by the Marines behind him. When he got to shore, he was helmetless and unarmed. I asked him what he did about losing his helmet and rifle, and he said he had no trouble getting replacements onshore. He didn't elaborate, and I didn't ask.
I cannot begin to imagine what it would be like to be involved in an amphibious assault. Judging from Dad's attitude toward them I'm certain that I never want to find out.