Gebhard Leberecht von Blücher rose to distinction in the Prussian military in his campaigns against Napoleon, earning the rank of Field Marshal.
He was also barking mad.
Blücher was paralyzed by fear for days at a time, perched in his chair, convinced that the French had made the floor too hot for him to stand upon. When he was forced to move from his chair, he danced from spot to spot, trying to stand on only one toe.
He also believed he had been sexually assaulted by a French soldier and as a result, he was pregnant and about to give birth to an elephant. His servants tried to mollify him by assuring him that it could be worse — he could have been raped by a French elephant, but nothing would calm his nerves.
Field Marshal Blücher had many fights with people only he could see, resulting in the destruction of a lot of furniture. When he was convinced that his head had been turned to stone, he pleaded with a servant to smash his head with a hammer.