Across its history, the United States military has seen more than a handful of men, ships, or aircraft embark on dangerous missions only to disappear seemingly into thin air without leaving a trace.
These disappearances continue to baffle historians and military leaders to this day, and leave us craving for answers despite extensive search efforts and advances in technology.
Here are the thirteen most mysterious disappearances involving the U.S. military that remain unexplained to this day:
1 – Disappearance of the USS Cyclops

The USS Cyclops was a collier (a type of cargo) ship built for the U.S. Navy before World War I. In March of 1918, the ship and its 306 crew members and passengers completely vanished without any trace. This represented the largest loss of life not involving an engagement with hostile forces in the history of U.S. Navy. The German government denied sinking the ship with U-Boats, which was the most common speculation at the time.
The Cyclops set out to sea from Rio de Janeiro in February of 1918 in the direction of Baltimore. The ship had originally traveled to Brazil to collect a shipment of manganese to take back to the United States; she was reportedly overloaded with the shipment and also had a cracked cylinder after departing from Rio, but was still deemed fit to travel. However, the Cyclops never reached Baltimore, and there were no sightings of it on its return voyage nor has the wreckage ever been found. The disappearance of the USS Cyclops remains a mystery to this day.
2 – Disappearance of Flight 19 and Rescue Team

On December 5th, 1945, five GM TBM Avenger torpedo bombers completely vanished without a trace over the infamous Bermuda Triangle. The planes vanished after having lost contact with the Naval Air Station base in Fort Lauderdale. In addition to the planes, all fourteen aviators in the aircraft went missing as well, in addition to the thirteen rescue team members of a Mariner flying boat that was later launched in search of the flight.
The disappearance of Flight 19 and the rescue team remains one of the biggest unexplained incidents involving the U.S. military and created a host of conspiracy theories. The idea that extraterrestrials had something to do with the disappearance of the planes was popularized in the 1977 Steven Spielberg sci-fi film Close Encounters of the Third Kind.
3 – Disappearance of Glenn Miller

Glenn Miller was a big band conductor and composer who is today considered the father of U.S. military bands. Miller initially gained popularity with his civilian band, Glenn Miller and his Orchestra. In 1942 after America joined World War II, he volunteered to join the Army as an officer to help entertain the troops; many other military bands would follow in his footsteps in the years and decades after.
On December 15th, 1944, Miller departed in a plane across the English Channel. The next day, the Battle of the Bulge began when the Germans launched a massive counterattack against the American and British forces in Belgium. All attention was focused on the unexpected German assault, so it wasn’t realized that Miller’s plane had gone missing until three days later. He was declared legally dead after a year, but the plane or the bodies of Miller and the other passengers were never found.
4 – Disappearance of Felix Moncla

On November 23rd, 1953, radars at the Air Defense Command Ground Intercept in Michigan identified an unusual object flying over Lake Superior. 1st Lieutenant Felix Moncla was dispatched in an F-89C Scorpion jet to intercept the object and identify it. Moncla rapidly closed in on the unidentified object at an altitude of around 8,000 feet, and both Moncla’s Scorpion and the object were being tracked on radar.
When the two icons indicating Moncla and the object got close together, however, they seemingly merged into one icon before continuing onward! All radio communication between Moncla and the Air Defense Command ceased working at that moment as well, and a search and rescue option failed to find Moncla or the object. As with Flight 19, the disappearance of Moncla created a host of conspiracy theories that he and his plane had been abducted by a UFO.
5 – Disappearance of a R6D-1 Liftmaster

On October 10th, 1956, a U.S. Navy Douglas R6D-1 Liftmaster was carrying a crew of 59 passengers and crew members from England to the Azores. The plane was last known to be traveling over the Atlantic around 370 miles southwest of Land’s End in England when it completely disappeared a couple of hours before midnight.
It is believed that the plane crashed into the ocean because a search and rescue operation found plane wheels and a life raft floating on the waters in the general vicinity of where the plane was last known to be, but these were unconfirmed as belonging to the same plane. None of the passengers were ever found or heard from again.
6 – Disappearance of the USS Scorpion

The USS Scorpion (SSN-589) was one of just two U.S. nuclear-powered submarines to disappear. In 1968, the Scorpion was traveling across the Atlantic from Virginia to the Mediterranean as part of Cold War operations against the Soviets when it completely vanished. While the wreck was eventually discovered after an extensive search and rescue effort, the discovery only created more questions than answers.
The Scorpion was found resting at the bottom of the ocean floor but the body of the submarine was inexplicably crushed, bent, and twisted and the bodies of the crew were missing! It’s unknown if the submarine crashed into something under the ocean, engaged a Soviet submarine in a battle and was hit by a torpedo, or had an explosion go off from the inside.
7 – Disappearance of the Crew of the Mary Celeste

On December 4th, 1872, the British ship Dei Gratia spotted the American maritime trading vessel Mary Celeste sailing at full speed near the Azores islands. There wasn’t anything strange about that except for one thing: everyone on board the ship was missing! The ship was in excellent condition with a full stockpile of supplies, but there was not a living soul onboard.
The last entry in the captain’s log was eleven days old and indicated that the crew were sailing the ship 500 miles away from its discovered location. This meant that the Mary Celeste had been sailing on its own for any time up to those eleven days. Further adding to the mystery was that the lifeboat of the ship was missing as well, but none of the crew were ever seen or heard from again. If the crew decided to abandon ship in the boat only to succumb to the sea, it’s completely unexplained as to why they would since there was nothing wrong with the ship itself.
8 – Disappearance of a B-47 Stratojet

On the 10th of March, 1956, a B-47 Stratojet that was armed with nuclear weapons completely vanished while flying over the Mediterranean Sea. The plane had taken off from an Air Force base in Florida and was en route to Morocco. It was refueled twice by a tanker aircraft while en route.
After the second refueling, however, the plane inexplicably ceased communication with any military base and never turned up anywhere! A French-based news agency later reported that the plane had exploded north of French Morocco, but there was no evidence for this supposed explosion and a wreckage of the plane was never discovered after an exhaustive search and rescue effort.
9 – Disappearance of the USS Proteus

The USS Proteus was a collier ship that was launched in 1912. The ship faithfully served the U.S. Navy until 1941, when it disappeared in (you guessed it) the Bermuda Triangle. While it was initially believed that she was sunk by a German U-Boat, the Germans kept meticulous records of enemy ships they managed to sink, and there were no records of them sinking the Proteus.
All that’s known is that the Proteus disappeared along with all 58 of her crew members. What’s fascinating is that the Proteus was a sister ship of the Cyclops like we mentioned before, which also disappeared in or near the Bermuda Triangle area.
10 – Disappearance of the USS Dorado

On October 6th, 1943, the the USS Dorado (SS-428) submarine set out from Connecticut to the Panama Canal on her maiden voyage. The Dorado was scheduled to arrive in just over a week…but it never arrived. An extensive search by sea and air was conducted in an attempt to locate the Dorado, but turned out empty.
One theory is that the Dorado was accidentally mistaken for a U-Boat and sunk by American patrol aircraft, while another theory is that it was struck by a mine that German U-Boats laid off the coast of North or Central America. In any case, the true reason for the disappearance of the Dorado remains unsolved to this day.
11 – Disappearance of the USS Grunion

The USS Grunion (SS-216) departed from Hawaii for the Aleutian Islands of Alaska on her first patrol in June of 1942. The Grunion successfully sank three Japanese destroyers en route. But one month later, the Grunion completely disappeared and was never heard from again…until 2007 when the wreck was discovered in the Bering Sea.
But still, the reasons for the Grunion’s sinking remain unverified. The Navy never received any reports that the Grunion was engaged in combat with hostile forces that could have led to its sinking, and furthermore, the bow of the submarine was discovered about a quarter mile away from the main body. The true nature of the Grunion’s sinking remains a mystery.
12 – Disappearance of US Navy PB4Y-2 Privateer

On April 8th, 1950, a U.S. Navy PB4Y-2 Privateer patrol bomber was conducting. reconnaissance mission on the Soviets over the Baltic Sea. It was a perfectly routine reconnaissance mission until the bomber was last seen in the airspace over the coast of Latvia…before disappearing completely.
The Navy immediately conducted extensive search and rescue operations in an attempt to locate the bomber or its crew, but these went nowhere. The United States accused the Soviet Union of shooting down the plane, but they denied it. The disappearance of this plane remains one of the biggest unsolved mysteries of the Cold War.
13 – Disappearance of the USS Capelin

The disappearance of the USS Capelin submarine (SS-289) is one of the biggest mysteries of the Second World War. The submarine was commissioned in the summer of 1943 and sank a Japanese cargo ship on her first patrol. On her second patrol that November, the Capelin set out from Australia with instructions to report her status in three weeks…but no status report ever came.
The Capelin had vanished, along with all 76 of her crew members. Some believe that the submarine may have struck a Japanese mine or been sunk by a Japanese vessel, but these remain unconfirmed.

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