18th RCT at Longstop Hill

My father (who died in 2001) was in the 18th Rgmt, 1st Bn, Co D (and as far as I know with the unit throughout the war, Africa, Sicily and Normandy). I'm currently reading American Iliad (By Robert Baumer and Mark Reardon) to try and get a better understanding of my Dad (who never talked about his war experience without breaking down), and I was shocked to come across this story on page 62 as related by the Co. D commander, Captain Sam Carter:

"About mid-morning this fully armed German patrol came down the road. Leading the patrol was one of my own men, with a dirty face towel at his hips and a pistol in the middle of his back that was being held by a young German officer. My man, a corporal, was fluent in German, and I learned they wanted me to surrender my unit and become prisoners of war".
The anecdote continued with Captain Carter telling the corporal (in English) to hit the ground when he gave the order to open fire, directing his unit to fire on the Germans at the same time, and ultimately the killing of the German officer and capture of several Germans as well as the capture of handbooks of information from the dead patrol leader.
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I believe that corporal could have been my father. He would have been a corporal at the time (promoted 3 March 1941) and he was also fluent in German and Polish (as he was born and had grown up along the border with Poland until 1931 when he immigrated to the USA). I also know that his only "souvenir" from the war was a German P-38 pistol. (He rarely brought it out and I do not know where it is today). If one were to survive such an episode I should think he might have taken the pistol. (And I understand the the P-38 was issued to officers in the German army). Dad also once told me (in tears) that the Germans referred to his unit as "Chicago gangsters". That story might have left such an impression.

I've been trying to hunt down anything which might help to confirm my suspicion that this was my father but have been hitting a lot of dead ends. Unfortunately, Sam Carter died in 2005 and his wife Norma passed on in 2009. Right now I'm trying to make contact with one of their children (to see if there are more things written by Captain Carter) as well as the book's authors. I know that Dad's records were lost in the St. Louis fire so it has been hard to find leads. If anybody out there has something that could help my search it would be much appreciated.

(I have posted this information in multiple places and hope that I have not breached protocol for the web site by doing so).