Who is Col.-Gen. Zeitzler, Commander-in-Chief of the O.K.H. from Lost Victories and what is their importance?

Colonel-General Zeitzler was Commander-in-Chief of the O.K.H. during the same period of time that Manstein was the commander of Army Group Don (Southern Army Group). Zeitzler agreed with Manstein's policy of an elastic defense. He also disagreed with Hitler's demands to hold onto all territories. Over time, Zeitzler came to the realization that he was the Commander-in-Chief of the O.K.H. in name only. Hitler made all of the decisions, he made none. Zeitzler argued with Hitler, trying to persuade him to adopt a better military policy on the Eastern front.