The Day Japan Bombed Northern Colorado
An Explosion Near Fort Collins
On March 19, 1945, eight-year-old Jack Swets was outside on his family’s farm near Timnath when he heard an odd buzzing sound.
Then came the fire.
A ball of flame struck a nearby field, throwing sparks into the air and leaving a narrow crater nearly four feet deep. Jack ran toward the house, pale and struggling to explain what he had just seen.
His father, John Swets, called the sheriff. Before long, the FBI and military intelligence were involved.
This was no farm accident. A bomb built in Japan had traveled more than 6,000 miles across the Pacific Ocean and exploded about seven miles from Fort Collins.
World War II had reached Northern Colorado.
A Weapon Carried by the Wind
By late 1944, Japan was losing the war, but its military had found a remarkable way to attack North America without sending a pilot or airplane anywhere near it.
The plan depended on a river of fast-moving air that few Americans knew much about at the time: the jet stream.
Japanese engineers built large hydrogen balloons, some roughly 30 feet across, and attached bombs beneath them. Once released from Japan, the balloons climbed to about 30,000 feet, caught the winter winds and began an unmanned trip across the Pacific.
The weapon was known as Fu-Go.
Each balloon needed to survive several days of changing temperatures. During the day, sunlight warmed the hydrogen and caused the balloon to rise. At night, the gas cooled and the balloon sank. An automatic system responded by releasing gas when the balloon climbed too high and dropping sandbags when it fell too low.
It was an ingenious piece of engineering attached to a terrifyingly simple idea: let the wind choose the target.
Japan launched more than 9,000 of the balloons between November 1944 and April 1945. The goal was to start forest fires, kill civilians and create fear across the American West. Only a few hundred were documented in North America, but they reached from Alaska to Mexico and as far east as Michigan.
And one found the Swets’s farm.
The Explosion Near Timnath
The Swets family farm sat south of Timnath, close enough to Fort Collins that the city’s history archive includes the attack in its World War II timeline.
According to a local account later shared by Fort Collins historian Barbara Fleming, Jack was near the family corral when he heard the buzzing. The blast produced flames estimated at 10 to 15 feet high. Investigators found a crater about 46 inches deep, along with part of the tail assembly from an incendiary bomb.
No one was hurt.
That fact feels less like an ordinary detail and more like a small miracle. A child had been outside. A working farm stood nearby. A weapon had crossed an ocean with no guidance system, no pilot and no precise target, yet it managed to explode within sight of the family home.
The story did not end with the first crater.
About a month later, John Swets was working the field when his tractor reportedly dropped into a hollow created by another underground explosion. A second device had detonated beneath the soil without the family knowing it. The tractor was damaged, but again, no one was injured.
Several balloon incidents were recorded in Colorado during the war. The Swets farm appears to have suffered the state’s only reported property damage from one.
The Government Wanted Silence
The attack sounds like the sort of story that would have filled a newspaper’s front page.
Instead, almost no one heard about it.
The federal government asked newspapers and radio stations not to report balloon sightings or explosions. Officials had two good reasons. They did not want to cause panic, and they did not want Japan to know the balloons were reaching North America.
The Swets family was told not to discuss what had happened. Local reporters cooperated. One account says a radio reporter who tried to broadcast from the farm was cut off mid-report.
The silence worked.
With little news coming from America, Japanese officials had no reliable way to measure the campaign’s results. Believing the weapons were largely failing, Japan stopped launching them in April 1945.
The press blackout also created a dangerous problem: civilians did not know what they might find in the woods or on a farm.
On May 5, 1945, a minister’s pregnant wife and five children on a church outing discovered a fallen balloon near Bly, Oregon. The bomb exploded, killing all six. They were the only known people killed by enemy action in the contiguous United States during World War II.
The government then warned the public about the balloons.
By that point, the Swets family had been keeping its frightening piece of Northern Colorado history quiet for weeks.
A War That Had Always Felt Far Away
Fort Collins was deeply involved in World War II long before the explosion.
Residents bought war bonds, collected scrap material and practiced blackouts. Farmers were asked to produce more food. Prisoners of war helped with agricultural labor. Colorado A&M, now Colorado State University, trained pilots and military officers, while faculty members took part in wartime research. More than 80 former students died in the conflict.
People here understood that the war was real. Still, most experienced it through ration books, newspaper headlines and empty chairs at family tables.
An enemy bomb landing near Timnath was different.
It turned a global war into a physical place: a field, a crater and an eight-year-old boy trying to tell his family what had fallen from the sky.
The Farm Became Another Fort Collins Landmark
The location later gained fame for something much more cheerful.
The Swets property became associated with Swetsville Zoo, the roadside collection of whimsical metal creatures created by Bill Swets. For decades, drivers near Interstate 25 and Harmony Road passed dragons, dinosaurs, insects and odd mechanical animals built from old machinery, car parts and farm equipment.
That means two of Northern Colorado’s strangest stories share the same ground.
Long before the metal animals appeared, the property had been struck by a weapon sent across the Pacific by the Japanese military. Thousands of people later drove past without knowing that a small piece of World War II history sat beneath the familiar local landmark.
The Most Unlikely Battlefield in Northern Colorado
The Fu-Go campaign failed to create the widespread fires and fear Japan intended. Most balloons disappeared into the Pacific or landed harmlessly in remote country. The damage on the Swets farm was small, especially when placed beside the scale of the war.
But that is exactly why the story is so easy to miss.
History does not always arrive with a monument. Sometimes it leaves a hole in a farm field, damages a tractor and disappears into official silence.
Today, Timnath is one of the fastest-growing communities in Northern Colorado. New neighborhoods, busy roads and commercial development have changed the area almost beyond recognition. Yet on a March afternoon in 1945, a paper balloon crossed an ocean, drifted over the plains and dropped an enemy bomb within miles of Fort Collins.
Written by Nathan Weinland, leader of the Weinland Team at RE/MAX Alliance
Phone: (970) 690-4088
Email: Sales@TheWeinlandTeam.com
Written by fortcollinsexperience
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