1811, September: The Double Life of Captain Fritz Alswanger
It was a day in September 1811 in the city of Dantzig, Prussia (now Gdansk, Poland), that Captain Fritz Alswanger, a knight of the Legion of Honor who was well-known, respected, and liked by both his comrades in arms and the city's population in general, was to be publicly branded as a thief and drummed out of the service. The reason for this was that a ring which had gone missing from a family Alswanger had lodged with had been traced to a man who claimed that the good Captain had sold it to him. When faced with the evidence Captain Alswanger both shocked and disappointed all who knew him by fully confessing to the crime.
In making this confession, Alswanger knew that that he would be expelled from the officers' corps with dishonor, and be banished from his homeland of France. Alswanger signed the confession, and the governor, who was most upset, ordered the Captain's sword to be taken and for him to be placed in jail; the court-martial trial was scheduled for the next day. Friends and comrades visited Alswanger in jail and urged him to offer up some form of defense to the charges; Alswanger politely refused all offers of help in the matter, stating that he would take his punishment as the law dictated.
The court-martial lasted only three hours, and Alswanger simply accepted his sentence, foregoing both the right to appeal against the verdict and/or request mercy from the emperor... this second option being something that the sentence recommended for him due to his previous good conduct and service. Alswanger's sentence was to be removed from service dishonorably, held in a prison for one year, then returned to the company he formerly commanded as a mere private.
Which led to the spectacle of the day in September. Alswanger was brought to a public square, where all the other commanding officers were gathered -- and they in turn were surrounded by what seemed to be the whole town and all the remaining soldiers -- and had his medals, badges, and other symbols of his command stripped from him. As handcuffs were being brought to be placed upon him previous to escorting him to prison, Alswanger requested a moment to speak with the general in charge... and what he had to say was more of a surprise than his admitting to the theft was. Captain Fritz Alswanger stated that he was not, in fact, Captain Fritz Alswanger... he was the son of a petty tradesman of Strasburg, who had assumed the identity of Captain Fritz Alswanger when the aforementioned had died.
An Identity Thief's tale
Once arrangements had been made for the local town hall to be used for the not-so-public confession, the general and a troop of officers sat and listened to the former "Captain Alswanger" explain how he came to hold the title which was not his.
To begin with 'Alswanger' stated his purpose in publicly admitting his crime and taking punishment for it, as well as now talking to the officers, was that he felt it was his duty to guard Alswanger's name from all disgrace; therefore he was now forced to separate himself from said good name so that the crime committed would solely belong to himself, the son of Diderici of Strausburg.
Diderici had been apprenticed to a shoemaker, and later traveled with gypsies and learned to play guiter, but could never find a steady job. One day he was at a lemonade shop in the Italian city of Aquila, when he found a group of soldiers looking at him excitedly, apparently talking about him. When Diderici looked over at them to discern what they were about, the group burst into a general laugh for no apparent reason. One of these soldiers walked over to ask Diderici his name... and when Diderici looked up, he understood what all the laughter was about. The soldier standing before him looked almost exactly like Diderici himself, even down to the cut of his beard, that they could have been identical twins! The soldier, happy to hear that Diderici was 'free' (i.e. "jobless"), asked if the shoemaker would like to serve as his valet, as apparently Lieutenant Fritz Alswanger -- for that's who it was -- thought the idea of having an identical twin as his helper was most amusing. Diderici gladly accepted the job, and went straight home with the Lieutenant that night.
Alswanger, Diderici said, would often dressed in the valet clothing himself to go and invite guests in his own name, always amused that no one could discern the difference between himself and Diderici. Alswanger even had Diderici wear his uniform and pretend to be him at one get together, though Diderici avoiding talking much lest the ruse be discovered by his rough speech. All was in fun until one cold and wet autumn night when Diderici assisted his somewhat drunk master Alswanger home. Alswanger was complaining of a violent headache and giddiness. He was given a cool bandage for his head and some lemonade, and soon set to bed to rest. When Diderici came in the morning to bring his master his usual chocolate, he found Alswanger stone cold dead... and instantly realized that he had an unforeseen opportunity. He switched shirts with his deceased master, then placed the body in his servant bed; then Diderici lay in the master's bed. He waited an hour and then called for his valet, with the result that the other servants in the house discovered the dead 'valet' in the servant's bed.
Diderici called doctors, and made a show of both concern and grief. Over the next three weeks, he pretended to be in a deep solemn mood -- merely an excuse to not interact with people who might note the switch -- and familiarized himself with Alswanger's letters and papers while practicing his signature. At the end of three weeks, a kind doctor suggested a change of scenery for the 'depressed' man, which was perfect: in moving to a new place, Diderici would leave behind everyone familiar with the original Alswanger, and be able to finally claim the identity fully. Soon, the new Lieutenant Fritz Alswanger was transferred from Italy to France, leaving behind all previous servants as well.
He had one last trial before his fraud could be fully accomplished, for Diderici found he was obligated to visit his "family" in Rome before he could go to France. He put this visit off for as long as he could as he taught himself Italian, but soon had to visit lest he raise too much suspicion from hesitation. Diderici had no problem convincing Alswanger's father and sister of his false identity, but he knew the mother was watching him. After only four days with the family, however, he received his orders to go to France, and then never had to directly interact with them again, just being sure to send letters to keep up appearances.
Once in France, the fraud was complete; he would no longer meet former associates of the original Fritz Alswanger, and so was able to act himself at last. It was Diderici who earned his way from Lieutenant to Captain, who won the hearts of the soldiers and townspeople, and the respect of his superiors. But that was now done; and with his confession complete, Diderici allowed himself to be taken to prison. Letters, papers, and a booklet labeled "My Will" found in Captain Alswanger's lodgings fully confirmed what Diderici had told them. Alswanger's mother, though saddened to hear her son had died, was relieved to hear her suspicions confirmed... for the replacement for her son was far less affectionate than her son had been towards her, so she had never quite felt right.
The details of the odd crime were sent to Emperor Napoleon Bonaparte. Months later, he replied. The Emperor's letter acquitted Diderici of the suspicion of having murdered Alswanger, but did hold him to task for stealing his name. Diderici was to be branded a thief between his shoulders, then temporarily confined in Weichselmünde prison, to be sent on to Brest where he would spend the rest of his life at the galleys. When the sentence was passed and Diderici was taken to the town square to be branded, a shower of filled purses and bouquets were thrown upon the platform, showing that most of the town's populace still loved their former Captain. Nonetheless, he was taken to Weichselmünde.
Diderici's stay at Weichselmünde proved longer than expected. As the year rolled from 1811 to 1812, Napoleon's empire began to unravel, and all attention was held by the chaos caused by this... so Diderici was never transferred to Brest and, for the most part, the whole affair was largely forgotten. Due to one unsuccessful escape attempt, Diderici was obliged to wear heavy fetters at the prison at all times.
In 1813, Weichselmünde itself was surrendered by the French back into Prussian hands. A 'revision' was performed, which was a review of the prisoners and their crimes, and civilians were largely freed and soldiers were added to the list of prisoners of war. Diderici was not to be found; in the prison register, the word 'missing' had been written by his name. When the commandant was questioned on this matter, he offered up his guess that the heavily-weighted Diderici had possibly leaped or fallen while walking on the walls into the Vistula River surrounding the fortress at a moment when he was not being watched... which sounds suspiciously like it wasn't accidental, though it is also true that Diderici had attempted to escape once already. Perhaps he had tried again, sucessfully or not.
The Source... and Other Weirdness
My current source for this tale is a dramatic 1864 presentation of the matter; I will try to find earlier sources to confirm the major details of the affair, but this seems to be the version of the tale that was picked up around one hundred years later to craft a false supernatural legend about Diderici's disappearance... to read more on that, follow the 'See Also' link below.