It was, at the time, the worst accident in railroad history.
The disaster - the Great Train Wreck of 1856, as it came to be known - has passed from the collective memory, but its impact reached far and wide.
Reported around the world, memorialized in ballads and spun into local lore, it was at once a cautionary tale of train travel and a catalyst for reform in a railroad system whose rapid expansion was outpacing its ability to be safe.
George Ditter, an Ambler native who lives in upper Montgomery County, heard about the train wreck as a child and has studied it ever since.
"Apart from shipwrecks, it was the first really big transportation disaster," Ditter said recently during a visit to the crash site, east of the Fort Washington train station.
"No one is clear on how many people died. . . . The death toll is at best an estimate."
Entire families perished in the wreck. People were burned beyond recognition, Ditter said. Bodies were never wholly recovered.
According to accounts of the incident, about 1,500 parishioners on their way to a church picnic boarded two North Pennsylvania Railroad trains at about 5 a.m. The first train pulled out of the depot about 20 minutes behind schedule.
Meanwhile, a train from Gwynedd was due to travel inbound on the same line - today part of the SEPTA R5 line to Doylestown.
Each train was aware of the other's scheduled run, Ditter said, and one or the other was to pull onto a siding at Edge Hill to let the other pass.
"The inbound train had a rookie conductor. He said, 'Let's go ahead, but we'll proceed slowly,'" Ditter said.
The outbound train was trying to make up for lost time.
As the inbound train rounded a curve, the engineer saw the shadow of Shakamaxon, the outbound's engine, on the embankment wall, hurtling toward him. It was too late to avoid impact, and the trains collided in a fiery explosion heard miles away, Ditter said.
The Norristown Register reported on the crash:
"It was a wreck of confusion, full of death and destruction. The three forward cars were completely crushed to pieces, and to make it still more horrible were soon enveloped in flames. The next two cars took fire and were entirely consumed."
The report went on to say that passengers were pinned in burning cars, "literally roasted to death."
No one on the inbound train, which had about 20 passengers, died.
The crash was followed by an outpouring of grief and a barrage of angry headlines in national newspapers, including one in the New York Times that declared "Railroad Butchery," according to Robert C. Reed in Train Wrecks: A Pictorial History of Accidents on the Main Line.
Public sentiment against unsafe conditions on the rails had been building for years, having been ignited by a series of deadly accidents in 1853, Reed wrote.
That year, a train in Connecticut ran through an open drawbridge and plummeted into a river, killing 46; several trains were involved in head-on collisions, killing nearly 40; and one mishap, a derailment, resulted in the much-publicized death of President-elect Franklin Pierce's 12-year-old son.
When disaster struck at Camp Hill (as the area just southeast of Fort Washington was called then), public anger deepened.
Rail safety was indeed a problem, according to Reed. Railroads were expanding quickly, often ahead of the capital needed to build sturdy cars, rails and bridges. Government grants and loans to build railroads were distributed only after rail lines were completed, which meant rail barons put a premium on speed in building rather than safety.
Ditter, a lawyer, said technological limitations also spelled disaster. Often there was only one track for inbound and outbound trains, and communication between trains and stations was nearly impossible, he said.
Cars were made of wood, making impacts more traumatic, and fires from the stoves used to heat the cars usually ignited them.
"For us, it's easy to say solutions were readily apparent," Ditter said. But at the time, technology had advanced only so far, he said.
The events of that day in Camp Hill 150 years ago continue to be a little fuzzy, despite a trial that brought certain facts to light but did not result in any convictions.
Tragically, William Vanstavoren, conductor of the Gwynedd train, killed himself shortly after the accident, apparently overcome by grief, Ditter said.
Contact suburban staff writer Cynthia J. McGroarty at 610-313-8113 or firstname.lastname@example.org.