Adolf Hitler protected a Jewish veteran from extermination during the Holocaust because the World War I vet served in the same unit as the leader of Nazi Germany, according to a Nazi-era letter unearthed by an historian.

Ernst Hess, a judge, was protected by Hitler because they served in the same unit during World War I. Hess was Hitler's commanding officer, according to the Associated Press.

The letter ordered Nazis not to harass H. in any way, referring to Hess, according to the AP.

Hitler's protection of the Jewish vet was documented in an Aug. 19, 1940, letter signed by a senior member of the Nazi SS.

It was a wonderful chance find, Susanne Mauss, the historian who discovered the letter, told the AP in a phone interview Friday. There had always been rumors, but this was the first written reference to a protection by Hitler.

Mauss found the letter written by Hitler concerning protecting the vet in the official archives of the Gestapo -- the name of Nazi Germany's secret police. The files were found among those about Jewish lawyers and judges, according to the AP.

While Hitler ordered Hess to be untouched, the judge's protection ran out in 1943, when Hess was sent into forced labor for two years and World War II ended.

The Jewish vet may have been protected by Hitler, but his family was not spared, according to the AP. His sister, Berta, was killed at Auschwitz. About six million Jews died in the Holocaust.

Hess had been offered reinstatement as a judge after the war ended, but the Jewish vet did not accept the offer, opting to work for the federal railways instead, the AP reported. The World War I vet died in 1983.

A historian familiar with Nazi Germany told the AP it was plausible that the letter is authentic, although the order may not have necessarily come from Hitler directly.

Thomas Weber, an historian at the University of Aberdeen, said records showed Hess and Hitler served in the same unit, and both men were injured in the Battle of the Somme.

Weber said it's possible the order in the letter came from someone close to Hitler who believed that protecting the Jewish vet would have been the Nazi leader's wish.

Weber particularly mentioned Fritz Wiedemann, an aide to Hitler who was known to be sympathetic to Jewish veterans, the AP reported.

I think it's likely that this was all done by Fritz Wiedemann, because he did the same in other cases involving Jewish soldiers, the historian told the wire service.