In 1941, when Rudolf Hess, the deputy leader of the Nazi Party, flew to Scotland in a harebrained attempt to negotiate peace with the Allies, Hitler "stripped his old comrade of all his offices," and appointed Martin Bormann in his place (4.23.268).
Shirer describes Bormann as "a more sinister and conniving character" than Hess (4.23.268). In the early years of the Nazi Party, he'd served as Hitler's second personal secretary, and Shirer characterizes him as having been "a molelike man who preferred to burrow in the dark recessesof party life to further his intrigues" (2.5.155).
As Germany's defeat in the Second World War came to seem more and more imminent, Bormann helped Hitler to plan and issue directives that would've laid waste to Germany and its peoples rather than see them fall into Allied and Soviet hands (6.30.121-126). As Shirer says, had their orders been carried out, "millions of Germans who had escaped with their lives up to then might well have died" (6.30.124).
Although he seems to have hoped that he could play a role in the government of post-war Germany, Bormann didn't survive the Soviet and Allied invasions. As Shirer records, he was among the group of "some five or six hundred survivors of the Fuehrer's entourage" who tried to escape Berlin when the Soviet Armies took it. According to the witness testimonies, Bormann probably swallowed poison "when he saw that his chances of getting through the Russian lines were nil" (6.31.219-20).