Rudolf Diesel was the 19th genius who invented the diesel engine—then vanished at sea under extremely suspicious circumstances.
1. His Disappearance Is A Mystery
Everyone has heard of the diesel engine. But few people have heard of its inventor; the curious engineer Rudolf Diesel. Diesel’s invention revolutionized the world—and probably cost him his life. His suspicious disappearance at sea remains one of the greatest unsolved mysteries of all time. The list of suspects in this pre-WWI whodunit will shock you.
2. He Was At Sea
On the stormy morning of October 9, 1913 the Dutch crew of the pilot boat Coertsen made a terrible discovery at sea: a bloated and severely decomposed body floating in the water. The crew knew that maritime protocol dictated that they recover the body for burial purposes. Curiously, however, the Dutch crew ditched protocol.
3. He Was Finally Laid To Rest
Despite the choppy seas, the crew of the Coertsen managed to haul the body onboard. They noted the “fine clothing” and collected a handful of personal items from the body for the purposes of identification. Then, they did something inexplicable: They returned the body to the sea.
However, they were certain they knew the identity of the body: the enigmatic inventor, Rudolf Diesel.
4. He Embarked On A Dangerous Voyage
Ten days earlier, on the fateful evening of September 29, 1913, Rudolf Diesel had embarked on a clandestine voyage aboard the Great Eastern Railway steamer, SS Dresden. His destination? A meeting of the Consolidated Diesel Manufacturing company in the heart of London, England where he promised to deliver his patented engine into the hands of the British Navy.
He would never make the meeting.
5. He Had His Last Supper
Amidst the dimly lit surroundings of the ship, Diesel ate his dinner in silence—likely thinking about the weight of his momentous decision. As the clock struck 10 pm, he retired to the seclusion of his cabin. He left word with the ship’s crew to wake him up at 6:15 am the next morning. However, the world would be the one getting the rude awakening.
6. He Didn’t Sleep A Wink
As instructed, the ship’s crew arrived at Diesel’s room at 6:15 am sharp. Only, instead of finding the famous inventor snoring away, they made an eerie discovery. Diesel was not in his bed. In fact, it didn’t even look like Diesel had gone to bed at all. A nightshirt, carefully arranged as if waiting for its owner, caught their attention.
As did Diesel's watch, strategically placed within view from the bed, ticking away as a silent witness to the mysterious scene.
7. He Left His Things Behind
As the ship’s crew began frantically searching for the disappeared Diesel, they only uncovered more curiosities. Pretty soon, however, their total bewilderment turned to outright dread as they discovered Diesel’s hat and neatly folded overcoat, concealed beneath the afterdeck railing.
Clearly, something terrible had happened to the world’s most famous and controversial inventor.
8. He Made Headlines
Diesel’s disappearance sparked an international media firestorm—and one of the greatest mysteries of all time. The official story was that Diesel had thrown himself overboard to his own doom. However, some newspapers ran with the shocking story beneath scandalous headlines such as “Inventor Thrown Into the Sea to Stop Sale of Patents to British Government”.
Everyone from the world’s richest man to the German Emperor would become a suspect.
9. He Was Destined For Greatness
To know how Diesel came to be a body floating in the water, we have to rewind. Born in Paris, France in 1858, Rudolf Christian Karl Diesel was the middle child of middle class parents. Despite this, however, there was little doubt that Diesel was destined for greatness. His German-born parents clearly saw his potential from the beginning.
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10. His Parents Gave Him Away
Diesel’s parents were of modest means and a baby genius was beyond their humble capacity. So, shortly after his birth, they gave him away to a family of farmers in Vincennes. The infant Diesel spent the first nine months of his life with these total strangers.
Sadly, when he returned home his family’s situation only worsened.
11. He Was A Child Laborer
Almost as soon as Diesel could walk, his parents put him to work. To help make ends meet, Diesel worked alongside his father in his workshop, making leather goods. It wouldn’t be too far-fetched to say that his parents pushed him from a young age. And we do mean that quite literally—they pushed him.
12. His Father Was A Tough Guy
Diesel’s father went to extreme lengths to toughen him up. One day, while walking in Paris, somewhere around the age of 8, Diesel and his father came across a corpse hanging from a tree. Instead of consoling the young inventor, however, Diesel’s father did something unexpected in an effort to teach his son an important lesson.
13. His Father Pushed Him
As they passed the corpse swinging ominously from a tree, Diesel’s father shoved him down the hill. Falling head over foot, Diesel rolled all the way down to a mucky pond just beneath the lifeless body. Terrified, Diesel clawed his way back to the top of the hill where his father explained that it was a “lesson in the hard knocks that life had in store”.
Life certainly had some hard knocks in store for Diesel.
14. He Was A Boy Genius
Even at a young age, Diesel’s genius was obvious to everyone around him. He excelled at school, far surpassing any of his peers. He also showed an outsized and precocious interest in matters surrounding the intersection of “social questions and technology”. Diesel very much believed that he could make the world a better place with his inventions.
If he survived long enough to implement them.
15. He Had The Heart Of A Poet
Diesel would become famous for his mechanical inventions. But, lurking beneath his technological genius lay the heart of a poet. In contrast to his father, Diesel’s mother was a gentler soul. She instilled in him a deep appreciation for the arts. In addition to being a mechanical genius, Diesel was also a “gifted piano player” and spoke three languages.
But it was too cruel a world for his gentle heart.
16. He Had To Flee For His Life
Just as Diesel was about to enter the prestigious Ecole Primaire Supérieure, fate threw a wrench in his plans and upended his life. With the outbreak of the Franco-Prussian conflict, all German peoples were banished from France. With nothing but the clothes on their backs, a 12-year-old Diesel and his family fled to the safety of London, England.
They did not, however, receive a warm welcome.
17. He Had No Place In The World
When the young and idealistic Diesel arrived in London, England his whole worldview shifted. As he crossed the London Bridge, looking out at a city filled with smoke stacks and smog, he realized that the world was run by industrialists for industrialists. There was no place for a poor refugee boy like himself with no fame and no fortune.
That is, no place unless he made one.
18. He Left London
Seeing his potential for greatness, Diesel’s parents knew that he couldn’t stay in London. Fortunately, they had family in high places. As it turns out, one of Diesel’s uncles was a prominent mathematics professor back in Augsburg. Once again, his parents made the sacrifice to ship him off. This time, however, he would not return.
19. He Was Top Of His Class
Unsurprisingly, Diesel excelled in Augsburg, studying mathematics with his uncle. He graduated top of his class and, shortly after that, the Royal Bavarian Polytechnic of Munich offered the little dynamo a scholarship to study engineering. Diesel was eager to continue on his path towards his greatness but his parents expressed grave reservations.
20. He Defied His Parents
Diesel’s parents wanted him to get a job instead of continuing his education, fearing that his foray into the upper echelons of engineering would bring him into dangerous circles. Against his parents’ wishes, however, Diesel accepted the scholarship to Munich where he studied under the famed German refrigeration magnet, Carl von Linde.
21. He Fell Ill
Just before Diesel was about to complete his final exams and secure his position as an eminent engineer, he found himself flat on his back. He fell terribly ill with a bout of typhoid and landed in the hospital. Thankfully, he recovered in time to graduate, but it wouldn’t be long before another incident landed him in the hospital again.
This time, he would not make a full recovery.
22. He Had A Secret Lab
With his health and his degree, Diesel returned to his hometown of Paris and took on the role of director at von Linde's refrigeration plant. By day, he showcased his engineering brilliance by filing numerous patents for the Linde Company. But, by night, he toiled away in secret on a revolutionary new engine that would change the course of history.
23. His Invention Blew Up In His Face
Under a cloud of secrecy, Diesel carried on working on his revolutionary new engine, making progress day by day. However, an explosive mishap nearly cost him his life. Diesel endured a lengthy hospital stay and suffered from persistent eyesight problems for the remainder of his days. Undeterred, however, Diesel powered on.
24. He Fell In Love
As the Elon Musk of his era, Diesel had plenty of women to choose from. Instead, however, he fell madly in love with one woman; the fearless Martha Flasche. The two tied the knot in 1883 and had three children together, Rudolf Jr., Eugen, and a daughter Heddy. Upon Diesel’s disappearance, however, the illusion of the happy family man dissipated like fog at sea.
25. He Made A Breakthrough
Finally, after toiling away in secrecy on his engine, Diesel made a major breakthrough. In 1897, he successfully built an engine that was more than two times as efficient as the ubiquitous steam engine. His new invention unlocked a world of possibilities, from submarines to clean-burning fuels. Now, he just had to find a way to announce his invention to the world.
26. He Was A Little Nutty
Diesel’s new invention promised to shake up the world. So what better way to display it than at the 1900 Paris Exposition in front of the whole world? To the amazement of the throngs of tourists, investors, industrialists, and even royalty in attendance at that year’s World Fair, Diesel ran his engine on nothing but nut oil.
27. He Attracted The Wrong Attention
With his new invention, Diesel stunned the entire world. There was no denying that he had made something revolutionary and he snagged the top prize at the 1900 Paris Exposition. But, while Diesel celebrated the debut of his fancy new contraption, he didn’t realize that he had attracted the attention of some very nefarious characters.
28. He Was Within Reach Of His Dream
Following his success at the 1900 Paris Exposition, Diesel turned into a worldwide superstar. From the farms of America to the factories in Europe, everyone was talking about Rudolf Diesel and his new engine. Finally, after his years of hard work in total secrecy, his utopian vision of a world powered by his efficient engine seemed in reach.
29. He Was Totally Green
Diesel was going green long before anyone had even heard of the term “net-zero”. He boasted that his new engine could “be fed with [vegetable] oils” just as he had displayed at the 1900 Paris Exposition. Seeing as though his engine could work on any type of oil, not just nut oil, the public began to call his invention the “oil engine”.
That was bad news for the world’s richest man.
30. He Made A Lot Of Enemies
Diesel was good at making machines, but terrible at making friends. As his reputation as a preeminent inventor grew, so too did his reputation as a fundamentally unlikeable individual. He was socially awkward and, according to his contemporaries, “sanctimonious”. Before long, Diesel had a list of enemies as long as his list of patents.
Enemies who would soon become suspects.
31. He Set A New Standard
Diesel’s new engine posed an existential threat to some of the world’s most powerful industrialists. Including the world’s richest man, John D. Rockefeller. The titan of America’s Standard Oil worried that, if everyone started using Diesel’s new engine, they wouldn’t need his petroleum anymore as any farmer could simply turn his corn into engine fuel.
Diesel, it seems, was stepping on Rockefeller’s toes.
32. He Rocked Rockefeller
In 1912, Diesel took direct aim at Rockefeller. The famed inventor went on a trip to America and promised that his invention could unlock the young country’s true potential. He openly boasted that any country that could grow food, could grow its own fuel if they used his engine. His declaration to “break the American fuel monopoly” that Rockefeller held made headlines.
33. He Was Paranoid
Like many other geniuses of Diesel’s caliber, the “mechanical Michaelangelo” was not easy to get along with. His peers and colleagues often described him as “ vain, oversensitive, and paranoid”. It was no surprise then that his abrasive personality made him a prime target for the ruthless Rockefeller. Amongst many other powerful people.
34. He Was Loyal To No One
Diesel might have been born in France, but with parents from Augsburg, he was German through and through. So, when the German Emperor, Kaiser Wilhelm II, learned that Diesel’s engine could help him build submarines and outpower the British Navy, he demanded fealty. Diesel’s only loyalty, however, was only ever to science and engineering.
Or, it would seem, the highest bidder.
35. He Had To Pick A Side
Diesel’s invention had reached a critical point. Rockefeller wanted to destroy it. The German Emperor wanted it all for himself. The British King wanted to unleash it on the high seas. Even the Russian oligarchs eyed it wearily. On the eve of WWI, with tensions higher than they had ever been, Diesel had to pick a side.
The wrong choice would be fatal.
36. He Was A Nervous Wreck
By 1913, one thing was obvious—Diesel’s new engine had changed the world. While that would have made most inventors very happy, it only compounded Diesel’s already anxious personality. Feeling that he was losing control of his invention, Diesel began to experience nervous breakdowns and fretted over how his work would change history.
He should have fretted about how his work would change—or end—his life.
37. He Chose His Fate
With the naval arms race between Britain and Germany heating up, Diesel had to pick a side. Much to the consternation and frustration of the German Emperor, the sought-after inventor decided to sell his services to the British. He joined the board of the Consolidated Diesel Manufacturing Company in London and set sail for his new fate.
That’s how Diesel ended up on the SS Dresden—and lost at sea.
38. His Son Identified His Belongings
On October 13, the Dutch crew of the Coertsen brought their findings to shore. They showed the personal belongings of the body that they had found at sea to Eugen Diesel, Rudolf Diesel’s son. Eugen confirmed that the items—a pill case, wallet, I.D. card, pocketknife, eyeglass case—belonged to his father. But something didn’t add up.
39. He Likely Jumped Overboard
No one knows why the Dutch crew of the Coertsen chose to throw the bloated-beyond-recognition body back overboard. After all, the entire world had spent nearly two weeks wondering what had happened to Rudolf Diesel. Nevertheless, evidence quickly began to emerge that the official story—that Diesel had taken his own life by jumping overboard—was the likeliest explanation.
40. He Was Not What He Seemed
With so many powerful enemies, it’s tempting to say that Diesel’s disappearance was a grand conspiracy. However, it’s equally likely that Diesel threw himself overboard. As it turns out, the famed inventor was even more enigmatic and complicated than his new engine. He had a deep well of secrets that began to emerge after his disappearance.
41. He Couldn’t Sleep
According to his friends and relatives, Diesel’s anxiety was even worse than the public knew. Following his disappearance, they revealed that he had suffered from terrible bouts of insomnia. They posited that he might have gone for a walk that night and, in a tired stupor, fallen overboard. However, the sea was still as glass that night.
And Diesel had many more secrets.
42. He Had A Bag Of Secrets
Just before embarking on his final—and apparently fatal—voyage, Diesel had given his beloved wife Martha a mysterious bag. He instructed her very specifically not to open the bag until the following week. When she finally did take a peek inside, the contents only gave rise to more questions and his disappearance only became even more suspicious.
43. He Had No Money
After her husband’s inexplicable disappearance, Martha couldn’t hold back her curiosity. She opened the bag that Diesel had given her and made a shocking discovery. He had left her more than $100,000 in cash and a series of bank statements that sent shivers down her spine. The famous inventor, as it turns out, was flat broke.
44. His Last Diary Entry Was Ominous
The fact that Diesel had been having financial troubles only gave more credit to the theory that he had jumped into the sea of his own volition. Another shocking discovery almost convinced detectives to call it a closed case. The only entry in Diesel’s diary on September 9, 1913, the day of his disappearance, was an ominous cross.
45. He Was On The Mend
Despite the mounting evidence, the world refused to believe that Diesel had taken his own life. Even though he had financial difficulties, 1913 had been a good year for him. It appeared that he was just on the verge of recovering from his money problems and the royalties from his engine were pouring in faster than ever.
Then there were the letters.
46. He Was A Happy Man
Whatever troubles he was facing with Rockefeller or the German Emperor, Diesel knew he could rely on one person: his wife, Martha. Throughout their happy marriage, right up until his last days, Diesel wrote glowing love letters to his wife. Nothing in those letters indicated that he might leap off a ship into the sea of his own volition.
47. He Was Friends With Edison
Not only did Diesel have a wife that he could rely on, but he had also managed to make some good friends. One of those friends was another famous inventor, Thomas Edison. Just one year before his disappearance, Diesel had traveled to America to spend time with Edison. Seeing his friend was stressed out, Edison advised Diesel to watch his diet and he would live to be 100.
Edison might actually have been right.
48. His Enemies Cleared Their Names
One year after his mysterious disappearance, speculation continued as to what could have happened to Rudolf Diesel on the night of September 29, 1913. Without any evidence (beyond clear motive) to implicate Rockefeller or Kaiser Wilhelm II, the world more or less accepted the going story. Diesel was having money troubles and he leapt overboard to his doom.
However, another theory soon emerged.
49. He Was Old News
Diesel’s disappearance was unthinkable to the early 20th-century world. It would have been as if Elon Musk had simply disappeared today. However, an even more scandalous story would soon take over the headlines and relegate Diesel to the back pages: WWI. Once conflict broke out across Europe, everyone forgot about poor disappeared Diesel.
So when a new theory of his disappearance emerged, almost no one noticed.
50. He Did Not Drown
In late spring of 1914, with the world on the verge of conflict, a new theory of Diesel’s disappearance emerged–one that no one could have predicted. According to a story in the Abend Zeitung newspaper, Diesel had not, in fact, drowned at sea on the night of September 29, 1913. Rather, they posited, he staged a daring stunt worthy of Houdini.
51. He Was Alive And Well
The Abend Zeitung reported that recently uncovered letters proved that Diesel had not drowned at sea. Rather, they claimed, he was alive and well, leading a new and secretive life in Canada. However, given the rising tensions of WWI—tensions that Diesel’s engine had helped to fuel—few people noticed the hair-rising story.
As such, Diesel’s disappearance remains the greatest unsolved mystery of all time.