Ok, this is a summation of a discussion in Germany. It is driven by historians who are inspired by post-colonial theory.
I cant discuss all arguments against the hypothesis, that the genocide against the Hereros is linked to the Holocaust. The most important IMO are:
1) The mass murder of the Hereros happened after the battle at the Waterberg by famine. The article tells the story of the Vernichtungsbefehl by Trotha. For the genocide the concentration camps werent as important. And the concentration camps were more connected to colonial concentration camps of other colobial powers, like the camps of the british in the Boer War. They were used to win a war, not to exterminate.
2) The mass murder of the Hereros was very controversial in the public of imperial Germany. After a debate in the german parliament Trotha had to leave his position. Even if supported by Schlieffen Trothas racist actions were more or less his own decisions.
3) The Holocaust in his evilness is defined by his absolute irrational nature in a modern rational society and state. Yes, the nationalsocialists believed that killing the jews would help win the war. But this was far from reality, only based in a pathological antisemitism. It may sound cynical, but Trotha and also the Generalgouverneur Leutwein, who was against Trothas policy, first of all tried to win a war.
makes flight stands for 1/300 scale aircraft.
