July 22, 2025

The Preparedness Day Bombing

The Preparedness Day Bombing

July 22, 1916. A bomb explodes during a “Preparedness Day” parade in San Francisco, killing 10 people and wounding another 40.

Cold Open


It’s 2 PM, on July 22nd, 1916, in San Francisco, California.

Marching along the street, 40-year-old Dr. Joseph Moss waves to the cheering crowds that pack the sidewalks.

It’s “Preparedness Day,” and the parade has been organized by San Francisco’s Chamber of Commerce. They want to show their support for an increase in defense spending by the government amid the ongoing war in Europe.

To his left and right, Dr. Moss is flanked by fellow veterans who fought in the Spanish-American War two decades ago. Now, though, he’s a prominent surgeon in San Francisco, but Dr. Moss hasn’t forgotten what he learned in the U.S. Army—he marches in perfect step with those around him.   

As a former soldier, Dr. Moss believes the United States has a responsibility to the rest of the world and should join the fighting in World War I. 50,000 other marchers today agree with him. But many in America would prefer to stay out of the conflict. Some of these isolationists have even made violent threats against today’s parade.

But as he continues along Market Street, Dr. Moss doesn't think much of these threats. But then, out of the corner of his eye, he spots something falling from a rooftop up ahead. It looks like a package or a small bag — Dr. Moss can’t make it out. But it’s trailing smoke, and as it lands among the crowd below — an ear-piercing explosion knocks Dr. Moss to the ground.

Through dust and smoke, Dr. Moss sees the vague shapes of men, women, and children staggering in shock all around him.

Dr. Moss’s medical and military training kicks in. Rather than run away from the blast, Dr. Moss gets to his feet and moves toward it. He pushes through the terrified crowd to the corner of Stuart Street. And there, Dr. Moss comes face-to-face with horrors he didn’t even see in combat.

In all, ten people are killed, and 40 others are wounded in this bombing, making it the deadliest act of terrorism in San Francisco’s history. But the evidence of eyewitnesses like Dr. Joseph Moss will be ignored by those investigating the attack. Instead, detectives will pursue an innocent man with false accusations and coerced testimony, leading to an extraordinary trial and a miscarriage of justice that will forever obscure the truth about the Preparedness Day bombing on July 22nd, 1916.

Introduction


From Noiser and Airship, I’m Lindsay Graham, and this is History Daily.

History is made every day. On this podcast—every day—we tell the true stories of the people and events that shaped our world.

Today is July 22nd, 1916: The Preparedness Day Bombing. 

Act One: Keeping Out of Trouble


It’s just after 1:30 PM, on July 22nd, 1916, in San Francisco, California, only half an hour before the terrorist attack on the Preparedness Day Parade.

33-year-old Tom Mooney elbows his way through the crowd, grumbling under his breath. The route to his apartment is blocked by thousands of flag-waving parade goers, and Tom must walk the long way around to reach his home.

Finally, though, Tom makes it to his apartment building. His wife is waiting for him by the front door. And for a moment, they scan the cheering crowds all around them. Neither of them approves of the parade—as far as they’re concerned, it’s not about being “prepared”, it’s about pushing America into military conflict in Europe. But that’s not what Tom is worried about right now.

For the last few months, he’s been followed and harassed by the San Francisco police because Tom is a well-known local political activist and labor leader who isn’t popular with the authorities in the Bay Area. It seems to Tom that the police are watching him for any hint of criminality, so they can swoop in and arrest him.

This constant surveillance has made Tom jittery, but he can’t see any police officers trailing him today. Perhaps because they’re all too busy with the parade. So, Tom and his wife enter the building and head up the stairs to their apartment.

Their intention is just to watch the parade as it passes by. They don’t like it, but protesting would only give the police what they want—an excuse to arrest Tom. But the quiet afternoon they’d planned falls apart.

Just a short while after they go upstairs, a bomb rips through the Preparedness Day Parade, killing ten innocent bystanders and wounding forty others. From the roof of their apartment building, Tom and his wife can see the smoke rising into the sky half a mile away, while a flood of terrified people rush away from the scene in the street below.

While they watch, investigators are already getting to work, and a few hours after the attack, a 38-year-old detective sits down opposite the District Attorney to update him on the incident.

Detective Martin Swanson is one of the men who have been tailing Tom for the past few months. And he believes that Tom and his fellow socialist radicals were responsible for another bombing on a local power station. Now, after today's attack, Detective Swanson is convinced that the two crimes must be connected. So he tells the District Attorney he has two prime suspects: Tom Mooney and an associate of his named Warren Billings. Detective Swanson speculates that Warren is likely the man who planted the bomb, but that Tom will be the true mastermind behind the crime.

In the aftermath of the bombing, the District Attorney is eager to see justice done swiftly, so he encourages Detective Swanson to pursue his theory.

And over the next few days, Swanson interviews Tom’s known associates, constantly pressuring them to link him to the bombing. Meanwhile, the city’s Chamber of Commerce puts up a $5000 reward for information leading to the arrest and conviction of the bombers. This money attracts the attention of an out-of-work waiter, who’s been telling anyone who will listen that he saw two men place a briefcase on the street moments before the explosion. Neither of the men fits the description of Tom Mooney or Warren Billings. But that doesn’t discourage Detective Swanson from leaping on the evidence to support his theory—and soon he finds even more willing witnesses.

A cattle rancher from Oregon comes forward with a claim that he saw Tom pass Warren a suitcase moments before the explosion. This is exactly the sort of information Swanson needed. And immediately, he arrests Warren Billings. But Tom Mooney is nowhere to be found. A warrant is put out for him. But in Detective Swanson’s eyes, his disappearance is just another sign that Tom is guilty.

News of the arrest—and the missing suspect—soon makes the national papers. Up in Montesano, Washington, those reports are read by Tom Mooney and his wife. They’re on vacation in this popular riverside town, on a trip they’ve been planning for months.

But the news from San Francisco means that their enjoyable break is now over. With a warrant out for his arrest, Tom decides to return to California to clear his name. He knows he didn’t commit the crime he’s accused of and hopes that a fair trial will confirm that. But to prove his innocence, Tom will have to face a police force convinced of his guilt, a public crying out for revenge, and a witness who will say anything to see him hanged.

Act Two: Getting His Man


It’s 5 AM, on July 26th, 1916, in San Francisco, California, only a few hours after Tom Mooney returned to California and handed himself in to the police.

Sitting in an interrogation room, Tom repeats his request for legal representation. The police officers across the table ignore him, though, and instead repeat a question of their own. They ask Tom again and again where he was when the bomb tore through Stuart Street. Tired from his long journey back to San Francisco, Tom takes a deep, measured breath before answering.

He tells the police exactly what he told them the first time, more than an hour ago. He insists he is completely innocent. And when the bomb went off, he and his wife were at their apartment on Market Street, half a mile from the scene. After calmly repeating his alibi for the fourth time, Tom again asks for a lawyer. But the officers still deny his request.

Tom is then led back to his cell, fuming. He knows he is innocent. But what’s worse is he’s certain that the men trying to get him to confess know he's innocent, too. After all, they were following him in the days leading up to the attack, and if he had been the bomber, they would've known.

But while Tom stews in his cell, a man he doesn’t recognize stops in front of the cell door and peers at him through the bars. It’s the out-of-work waiter who saw two suspects leave a suitcase near the bomb site. In his original statement to the police, the description he gave was nothing like Tom Mooney. But now, as the waiter gazes at Tom in his cell, he changes his mind. He gives a nod to Detective Martin Swanson, who’s standing beside him. And with a satisfied smile, Detective Swanson leads the waiter away.

Tom doesn’t fully understand what’s just happened. But he knows that if Swanson is pleased, it can’t be good news. And that’s not the only setback in Tom’s attempts to clear his name.

Outside of his cell, a trial by public opinion is underway—and Tom is losing it. His name is in every newspaper in America. Journalists are running wild with the idea that Tom and a gang of socialist anarchists were behind the San Francisco attack. Some reports claim that Tom fled the city after the bombing, even though the vacation was planned long before. Others claim that one of his crew is about to turn on him and confess to his part in the crime.

It's all inaccurate or wildly speculative, but the media coverage means that when Tom Mooney eventually appears in court in early 1917, most of the public have already decided he’s guilty. And nothing they hear from the trial convinces them otherwise.

One of the men testifying against Tom is a 60-year-old cattle rancher from Oregon. He’s a prosecutor's dream. Kind-natured and affable, when he speaks, the jury sits forward and listens. When he cracks a joke, the courtroom erupts into laughter. And most importantly, when the rancher recounts his tale of seeing Tom Mooney and Warren Billings together before the explosion, the jury believes every word.

Tom’s lawyer pushes back. They claim chief investigator Detective Martin Swanson is pursuing a vendetta against Tom, encouraged by a District Attorney looking for a quick conclusion. But it’s clear that the jurors aren’t impressed by this argument.

So, Tom pins his hopes for acquittal on what he thinks is hard evidence. The Preparedness Day Parade was well-documented. There are countless photographs of the moments before and after the explosion—and Tom is in one of them. It shows him at his apartment building, just as he always said. Even better, the photograph of him has a clock in the background, showing the time was just a few minutes before the explosion. It would have been impossible for Tom to have been the bomber.

After it finishes presenting this evidence, the defense makes its closing statements, and then, it’s time for the jurors to consider their decision. Despite all the negative press and the false testimony from the prosecution witnesses, Tom believes the photograph will clear his name. But the jurors are more impressed by a charming rancher than a blurry photograph. And after six and a half hours of deliberation, they return with a guilty verdict.

Tom is convicted of murder in the first degree. His alleged accomplice, Warren Billings, is also found guilty. These verdicts are met with pandemonium in the courtroom and relief outside. As far as most of San Francisco is concerned, Tom is a brutal terrorist who deserves execution. But not everyone will be left convinced by the court’s verdict. The evidence that led to the conviction will be reexamined. And a movement will emerge to save Tom Mooney’s life.

Act Three: A Long Wait For Justice


It’s January 7th, 1939, at San Quentin State Prison in California, over 22 years after Tom Mooney was sentenced to death.

Tom looks up at the clear blue sky above him and a weary smile crosses his lips. When he was arrested in 1916, he was in his mid-thirties. Now, he is closing in on 60. He suffers from jaundice and ulcers. He's lost half of his life to a crime he did not commit.

In the aftermath of Tom’s conviction, the federal government became concerned about the fairness of the trial. President Woodrow Wilson set up a commission to investigate. And that commission discovered evidence that Tom had likely been framed, and, just two weeks before his scheduled execution, Tom’s sentence was commuted to life imprisonment.

In the eyes of many, that was still an injustice, and a campaign began to win Tom’s freedom. And over the years that followed, the key evidence against him fell apart. The testimony of the charming Oregon rancher was proven to be entirely fabricated. The prosecution’s star witness was 200 miles away from the scene of the crime when he supposedly witnessed Tom Mooney and Warren Billings exchange the bomb. And the waiter who had identified Tom at the police station confessed that he hadn’t actually gotten a good look at the bombers, but had been told he’d get a larger slice of the reward money if he pointed the finger at Tom.

Even with this new evidence, however, the Governor of California was unwilling to release a man known to be a radical labor activist. The legal system at the time also gave little room for convictions to be overturned through the courts. So, Tom would have to wait until 1939 and the election of a new Governor for justice to finally be done.

And now, finally, he's been offered an unconditional pardon. He walks out of San Quentin a free man, to find more than 200 vehicles filled with supporters awaiting him, lining the roads outside the prison ready for a procession to take him home. His so-called accomplice, Warren Billings, will also be released later that year. But Tom will not have long to enjoy his freedom. He will die at the age of 62, only three years after leaving prison.

Detective Martin Swanson’s vendetta against Tom distracted the police from any hope of finding the real perpetrators. All criminal investigations ended once Tom was behind bars, but historians will later point to the followers of the Italian anarchist, Luigi Galleani, as the likeliest culprits. They launched a deadly series of bombings all across America in 1919 that bore some similarities to the San Francisco attack. But no definitive proof was ever found, and it is still a mystery today precisely who was responsible for the bombing at the Preparedness Day Parade on July 22nd, 1916.

Outro


Next on History Daily. July 23rd, 1982. Three people are killed when a helicopter crashes on the set of Twilight Zone: The Movie.

From Noiser and Airship, this is History Daily, hosted, edited, and executive produced by me, Lindsay Graham.

Audio editing by Muhammad Shahzaib.

Sound design by Mollie Baack.

Supervising Sound Designer Matthew Filler.

Music by Thrumm.

This episode is written and researched by Owen Paul Nicholls.

Edited by William Simpson.

Managing producer Emily Burke.

Executive Producers are William Simpson for Airship and Pascal Hughes for Noiser.