Who is Hauptmann Wesreidau from The Forgotten Soldier and what is their importance?

Herr Hauptmann (Captain) Wesreidau is the company commander under whom Sajer serves from the fall of 1943 until Wesreidau's death in the spring of 1944. Wesreidau is portrayed as the consummate German officer—always in complete control of his emotional and mental state, wholly devoted to the German cause, fully competent in military tactics and leadership, and utterly fearless. His men are devoted to him.