No, it’s not a violation of Henkster’s Law. The early and unexpected demise of a major historical actor is an exception. Frederick William appears to have had a moderate view of foreign policy. He was one of the voices who advocated restraint in not humiliating France after the Franco-Prussian War. Had he lived, I doubt he would have deliberately antagonized Britain the way his son did. However, he was not going to live forever, and sooner or later the neurotic William II would send German foreign policy off the rails. Also, WW1 was as much the instigation of von Moltke the Younger and the General Staff as it was of the Kaiser, maybe more so.
So had Frederick William lived a long life, it might have been more likely a postponement of WW1 rather than an avoidance of it.
Kaiser Billy's problems began at birth, to his 17 year-old mother, Queen Victoria's daughter, Vicky.
It was a difficult birth contributing to permanent damage:
And efforts to correct his physical defects may well have contributed to his psychological issues.
Vicky sketched the machine to show her mother, but begged her to ensure that if the little boy visited Windsor, No one should see him with this machine on... not the servants or brothers and sisters and that it should not be talked about as it would be very painful to us.
As an adult Wilhelm too would contrive to hide his disability and in photographs always held gloves, a gun or a sword to disguise his withered arm."
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