In the battle of Smolensk in early July, 1941 the German Army captured some 600,000 Russians in a three-day period.
I didn’t watch the entire presentation the ret’d general had, but this (the Russian-German part of WW2) was his post-service life work.
There were entire campaigns with multi-millions of men that are essentially missing from history books.
And, it’s generally acknowledged that the battle of Kursk was the largest assemblage of tanks ever brought into war. Nope, he had another battle that had a greater number of tanks and men that is curiously missing from all known histories. Turns out, that most histories of the great battles were derived from one source-—not one particular source, but a single source. Thus, later recounts of battles and the resources involved ended up repeating prior misinterpretations or counts of materiel.