10 Unsolved Mysteries of World War I

It's been over a century since World War I ended in 1918, yet even today some of its most fascinating parts are shrouded in mystery. Despite the wealth of information and research available on the subject, most of these mysteries will likely never be solved, as much of the evidence now lies beneath decades of other wars, such as World War II.

10. Private John Parr

Born in 1898 in north London, John Parr joined the British military as a cyclist scout. His job was to ride ahead and gather information on enemy positions, although sadly his life came to an end just 17 days after Britain entered the war. Private John Parr would become the first British soldier to be killed on the European front during World War I, although to this day we don’t know exactly who killed him or how.

Parr was last seen before the Battle of Mons in August 1914. Reports from the battlefield suggested that he was likely killed by rifle fire from a German cavalry patrol, and that this probably happened during the fighting. However, no one saw him, and his partner returned to camp from a reconnaissance mission unharmed. Furthermore, German units did not reach British lines until well after the supposed date of his death, so there is a chance that Parr was killed by a native or, worse, by one of his own comrades.

9. The Lost Romanov Treasure

Before the outbreak of World War I in 1914, Russia had the third largest gold reserves in the world after the United States and France. Much of it was taken out of the country by the anti-communist White Army led by Admiral Alexander Vasilyevich Kolchak, who seized power after the Russian Revolution of 1918. This could be traced back to 1920, when the White forces suffered a decisive defeat at the hands of the Bolsheviks, with all their treasures seized and returned to the Russian government.

But when they checked, over 1,600 tons of gold was missing, and we still don’t know where it could be. One theory is that it’s buried in several places inside the city of Omsk, as that’s where the White Army was based in the largest numbers. It could also be at the bottom of Lake Baikal, which is the largest freshwater lake in the world by volume, making it difficult to explore.

8. Nurse Maule's suitcase

Back in February 2013, a mysterious suitcase was discovered in the psychology department of Abertay University in Scotland. It was filled with items from the First World War, including photographs, postcards and letters. Although we now know that it belonged to a nurse at Dartford Military Hospital in Kent named Margaret Maule, that’s really all we know about it.

We don’t know how it ended up in Abertay, or why none of Maule’s relatives ever claimed it in the past. There is no record of Maule ever visiting Abertay, and some have speculated that it may have been donated to the university by a family member who didn’t realise its significance, or simply left behind by a former student with some connection to Maule. While the suitcase’s contents are fascinating and provide a rare first-person look at the so-called Great War, there are still many mysteries surrounding how exactly it ended up where it did.

7. USS Warship "Cyclops"

USS Cyclops disappeared in early March 1918, making it one of the first mysteries to emerge from the now-infamous Bermuda Triangle. It was a collier, or a type of ship used to carry large quantities of coal, and was also one of the largest ships in the U.S. Navy at the time. Its loss — along with the more than 300 sailors on board — remains a mystery to this day. Curiously, two sister ships — the USS Nereus and USS Proteus — disappeared somewhere in the same area several years later, in 1941.

Theories range from German U-boats to massive sea monsters, though most fail due to lack of evidence. The sheer size of the vessel, coupled with the lack of distress signals or signs of wreckage, led many to believe that something unusual had happened to the ship and its crew. Some of their descendants have continued their own investigations into the incident, though with little success.

6. Red Baron

Manfred von Richthofen, better known as the Red Baron, was one of the most famous pilots of World War I. He was a German flying ace who shot down 80 enemy aircraft during his career as a fighter pilot. However, his death in April 1918 has been shrouded in mystery ever since.

We know it happened in the Sommyvo region of France, where he was involved in a high-stakes battle against Canadian ace Wilfrid May, although it is unclear who shot down his plane. We also know that the fatal bullet was fired from an Australian Vickers machine gun, entering his right side chest and exiting through his left chest. Although many British, French and Australian soldiers shot him with similar weapons, and some even claimed to have done so in the years since, we still do not know who fired the fatal shot.

5. Bela Kiss

Béla Kiss was a Hungarian serial killer who was drafted into the Austro-Hungarian army during World War I. While he was away, rumors of his death at the front prompted his landlord to go to the house and vacate it for the next occupant. There he discovered 24 corpses in various stages of decomposition, leading to a massive search operation in Hungary and surrounding countries.

Kiss was never found, as the wartime chaos in Europe made it impossible to pinpoint his exact location. According to one report, he was nearly captured in Serbia later that year, though he reportedly escaped by placing a dead soldier in his place as bait. In the years since his disappearance, Kiss has allegedly been spotted in various locations around the world, including Romania, Turkey, and even New York City.

4. Diary of Mysterious Sketches

Sometime in the 1970s, a mysterious diary was found in the archives of the University of Victoria in Canada. Filled with sketches from the front lines of World War I, the only initials found on it were "JM" and we still don't know who it was.

The contents of the diary are varied, with landscapes, buildings and people caught up in the war depicted in a variety of ways, often in great detail. The dedication on the first page reads "To my daughter Adele", and the diary features the insignia of the British Royal Cavalry and Royal Field Artillery, where J.M. is thought to have served during the war. This has led some people to believe that he was a British soldier serving in France or Belgium, although his exact identity remains largely unknown.

3. The Florentine Diamond

The 137.27-carat Florence Diamond was one of the largest diamonds ever mined. It was purchased by the Portuguese governor of Goa, Ludovico Castro, in the late 16th century and eventually ended up in the hands of the Medici family in Florence. It was passed to the Habsburg dynasty after the Medici's death, where it remained until Austria's defeat in World War I.

The stone was last seen in 1918 at an exhibition in Vienna, and has since disappeared from public view entirely. One theory is that it was taken by someone close to the Austrian imperial family and smuggled out of Austria, possibly to South America or the United States. Another suggests that it was sold to a collector in Europe, and that the stone has been in their private collection ever since.

2. Sea monster

In October 2016, the remains of a German U-boat from World War I were discovered off the coast of Scotland. Sonar scans and videos taken by underwater drones showed the wrecked submarine lying almost upright on the seabed, raising many questions about what happened to it. According to marine archaeologist and historian Innes McCartney, it could have been UB-85, although that's really all we know about it.

According to a German submarine crew, this particular UB-85 was attacked by a giant sea monster while on the surface recharging its batteries during the war. It was badly damaged in the battle, forcing its crew to abandon it before it sank in the Atlantic. However, British forces in the region said it was instead sunk by their patrol boat HMS Coreopsis April 30, 1918, although this incident was never officially confirmed by either side.

1. Who started the war?

For a war that changed the world more times than we can count due to its sheer scale, it is surprisingly difficult to pinpoint exactly who started it. The answer is not as simple as it might seem, because while we know the immediate trigger—the assassination of Archduke Franz Ferdinand by a Serbian nationalist—we still don’t know how the event went from being an international incident to one of the largest wars in human history.

Different historians have different views on the subject. While some believe that Germany bears direct responsibility, others say that the collective imperial interests of Germany, France, Great Britain, Russia, and Austria-Hungary ultimately led to the massacre. Some have even accused Serbia of complicity in the Serbian state's murder that started it all.