Time travel novel or series involving a professor at the Citadel who identifies the point of deviation

Question

There were two apparent timelines - the 1st was thought to be unchangeable until the plot happened; a key person in identifying the point of deviation between the two timelines was a professor at the Citadel military college in South Carolina, in the present day, who retained his memories from the previous timeline and who becomes interested in his student (a pilot hero, who I think became a cyborg, but do not take my word for it).

The professor was like a second generation German immigrant - this became important to the resolution of the POD.

Answer 1

Possibly The Gordian Protocol by David Weber.

I never actually finished this book (I read just over half of it a few years ago) but some of your elements seem to match my memories of it. It follows Doctor Benjamin Schröder, Chairman of the Castle Rock University history department, who teams up with Commander Abramowski, a highly decorated Navy fighter pilot, after he has what he initially believes to be a psychotic break, where he's flooded with memories of our timeline, where the Holocaust happened.