Ringo does this enough that it could almost be called his signature style. Just one, of the numerous examples of this is early in a A Hymn Before Battle O'Neal wants to speak with a science fiction author named David who specializes in space naval combat. This is probably a reference to either David Weber or David Drake, fellow Baen Books writers with whom he is friends.
Another example of this is Joe Buckley, although his character wasn't specifically given a full name until the third book in the Posleen War Series.
O'Neal himself is a former military man in the 82nd Airborne Division who left the service and went into private life in a technology-related job. Guess what Ringo was doing before he got his book contract?
Colonel Cutprice is explicitly based on Colonel David Hackworth, one of the most decorated soldiers in the US Army.
What Could Have Been: According to the afterword of Watch on the Rhine, apparently, Watch on the Rhine was going to be a shorter novella paired with Back to Bataan, a novella that was also a collaboration between John Ringo and Tom Kratman about the Japanese-assisted defense of the Philippines from the Posleen. However, the story of Watch on the Rhine grew beyond the planned 45,000 words and turned out to be more interesting than Back to Bataan.