When the US Army Tried Bombing Open a Frozen River

The scene in the skies over the Susquehanna River Valley on March 9, 1920, was something out of a World War I dogfight. Airplanes were still a novelty in 1920, yet a two-seater biplane circled over the Pennsylvania-Maryland border, where the Susquehanna River had been choked with ice for nearly three months.

Veterans of World War I might have recognized the plane as a de Havilland DH-4 bomber, an American-made military plane with the unfortunate nickname “The Flaming Coffin.” It was rare enough to see a U.S. Army Air Service plane in action, but nothing prepared onlookers for what happened next.

The small airplane circled the river a few times, then swung high into the slate-gray sky. Then, with the roar of its 12-cylinder Liberty engine echoing off the ice below, the plane entered a steep dive. As the plane pulled out of its nosedive, the pilot released his payload—a 112-pound bomb loaded with TNT.

The heavy bomb broke cleanly through the thick river ice and detonated with a rumbling roar. The explosion blasted a hole in the ice 400 feet wide and sent a plume of black water 100 feet into the air. The percussive shockwave was powerful enough to shatter windows in the watchtower of a nearby railroad bridge.

The river ice—as thick as 16 feet in places—groaned and cracked, but otherwise withstood the aerial onslaught. In the battle to free the Susquehanna River from a potentially devastating ice jam, the Army was going to need more firepower.

An ice jam or ice dam is an obstruction formed by huge chunks of ice that can pile up as high as a two-story house in frozen rivers. The ice wall acts like a natural dam, diverting the flow of the river and causing serious flooding in riverside communities.

An ice jam can form when a long, bitterly cold winter is followed by a sudden spring thaw. During the prolonged cold weather, the river completely ices over in a thick sheet running from shore to shore. When the weather warms up in early spring, snowmelt and rain swell the river below the ice, pushing upward on the frozen lid.

The thick ice sheet then cracks under pressure into massive hunks that break free and start to float downstream. The problems start when the ice chunks get snagged—on bridges, turns or narrow sections of the river—and start to heap on top of each other.

“Imagine a pile of giant bricks, but they’re all made out of ice,” says Adam Zurn, a teacher and local historian from Lancaster County, Pennsylvania, who runs the website Uncharted Lancaster.

An ice jam is a stunning sight to behold, with stacked shingles of ice sheets forming an impenetrable, craggy wall. But ice jams can turn sinister when river levels rise quickly with the spring thaw. First, water backs up behind the ice jam (now an ice dam) and floods the riverbank. Then, if too much pressure builds behind the thawing wall of ice, the frozen dam will burst open with a violent release.

“Obviously, flooding alone is terrible,” says Zurn, “but what makes ice jams so much worse is now you've got these giant projectiles riding along with the water and just smashing into stuff—razing buildings and anything else that gets in their way.”

That’s exactly what happened during the Great Ice Flood of 1904. That winter, the Susquehanna River was locked under another thick sheet of ice. It was solid enough that horse-drawn wagons delivered goods across the mile-wide frozen river. As the weather warmed in March, small Pennsylvania towns like Collins and Safe Harbor prepared for the usual spring flooding.

But soon the ice sheets broke into chunks and coalesced into massive ice jams that dammed the Susquehanna, already running fast and high. According to reports, the blockaded river rose 10 feet in five minutes. It wasn’t long before the sheer weight of the water broke through an ice dam, triggering a tidal wave carrying car-sized hunks of ice.

The village of Collins was completely wiped out. Homes and businesses were ripped from their foundations and washed downstream. All that was left standing in Collins was a lone railroad control tower overlooking a field of mud, ice and debris.

Similar fates awaited towns like Bainbridge, Marietta, Columbia and Wrightsville, where stone-and-iron bridges were lifted from their foundations and railroad stations were carried miles downstream. In Safe Harbor, river-borne icebergs damaged homes so badly that residents sold them for salvage for $30 each.

“The 1904 ice flood was about as bad as they get in the Susquehanna River Valley,” says Zurn.

In the winter of 1919-20—with memories still fresh of the carnage of 1904—the stage was set for another potentially catastrophic ice jam along the Susquehanna. Thanks to extremely cold weather, the river had been frozen solid for 83 days. As Zurn wrote in a blog post about the 1920 ice jam, the Susquehanna River had, “for all intents and purposes, become a glacier.”

That “glacier,” as thick as 16 feet in places, still hadn’t budged by early March. Anxious residents knew that the spring rain and snowmelt would be arriving soon. Zurn says that the Susquehanna River is fed by a drainage basin covering 27,000 square miles, meaning that rainfall as far away as New York makes its way into the river. When all that water arrived in the Susquehanna River Valley, it would create the exact same conditions that triggered the disastrous 1904 ice floe.

“At this point, people are moving things to higher stories or completely evacuating out of fear,” says Zurn. “Local officials and businesses are also worried about more railroad bridges being wrecked. The whole economy at that time ran by rail, so another ice floe could have a huge crippling effect. The destructive power of these things is hard to imagine.”

The residents of the Susquehanna River Valley didn’t have to imagine. They knew the devastation of an ice jam firsthand, and they were willing to try just about anything to stop it. That’s when the Army came calling.

In 1917, as the U.S. entered World War I, the Army needed more testing sites where it could develop new munitions and weapons, like trench mortars and air defense guns. One of those new testing sites was the Aberdeen Proving Ground, located less than 20 miles from the mouth of the Susquehanna River.

There was no Air Force in 1920, just the fledgling Army Air Service. The Army experimented with small fighter planes and bombers during World War I, but there was still a lot to learn about the promising new war technology. So when Colonel H. W. Scull at the Aberdeen Proving Ground heard about the ice sheet threatening to trigger another damaging flood, he saw an opportunity.

“The Army had all this new technology, specifically aircraft and high explosives, and they were looking for ways to use it to prove its value,” says Zurn.

Colonel Scull called in one of his ace bomber pilots, Colonel René R. Studler, who was commander of the 258th Heavy Bombardment Squadron at the Aberdeen Proving Ground. Studler’s mission was simple—drop bombs on the stubborn Susquehanna ice until it cracked open and washed away. He was more than up to the job.

The target of Studler's attack was a stretch of the frozen Susquehanna upstream from the town of Port Deposit, Maryland. Because of its location near the narrow mouth of the Susquehanna, Port Deposit was particularly vulnerable to ice jams. In 1920, the river ice near Port Deposit had piled into an extra-tall formation that locals called an “ice gorge.”

On March 9, Studler cruised 500 feet above the Susquehanna in his De Havilland DH-4. Newspaper reports from the time don’t indicate if anyone on the ground knew what was about to happen. Studler angled the DH-4 into a nosedive and dropped a 112-pound bomb into the heart of the ice jam.

At that very moment, a passenger train was crossing the nearby Baltimore & Ohio Susquehanna Railroad Bridge. Zurn says that it must have been quite a shock to see a World War I bomber outside the window and feel the train car shake with a massive explosion.

The first bomb punched a hole in the ice larger than a football field, but didn’t shatter the ice sheet into fragments as hoped. Since Studler’s plane could only carry one bomb at a time, he returned to Aberdeen Proving Ground to reload. The round-trip took 17 minutes and crowds of spectators began to gather to watch the unexpected air show.

“Army Flyers Shatter Susquehanna Gorges with Big TNT Bombs” ran the headline in the next day’s edition of the Lancaster News Journal. “Officials Pleased with Success of Experiment—More Powerful Explosives Will Be Used Today.”

For the second day of bombing, the Army tried increasingly bigger bombs—230-pound charges, then 250 pounds and finally 500-pound behemoths.

“A total of 5,000 pounds of TNT was dropped on that river over the course of two days,” says Zurn. “I’d say that’s pretty aggressive.”

The repeated bombing of the Susquehanna River definitely had an effect. Large sections of ice broke free and floated down the river, only to get snagged around bridge piers or islands and pile up again.

But then on March 12, three days after the initial bombing, the Susquehanna ice jams loosened up and started to move, floating peacefully past Port Deposit and into the sea. Some people credit the aerial attack, while others say it was the natural result of a few warm, sunny days.

“The jury's still out whether the bombing did anything or if the ice jam just kind of naturally broke in the next day or so,” says Zurn. “They're not 100 percent sure, but I'm sure the Army was happy to take credit for saving the day.”