The Preparedness Day Bombing

Summary

History Daily – "The Preparedness Day Bombing" (July 22, 2026)

Host: Lindsey Graham
Podcast: History Daily
Episode Theme: The 1916 Preparedness Day Bombing in San Francisco—America’s deadliest act of terrorism at the time, the flawed pursuit of justice, and the decades-long fight to clear the names of those wrongfully convicted.

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Episode Overview

This episode of History Daily delves into the events of July 22, 1916, when a bomb tore through San Francisco’s Preparedness Day Parade, killing 10 and wounding 40. Host Lindsey Graham reconstructs the attack, the ensuing investigation, and the sensational trial that led to the wrongful conviction of Tom Mooney and Warren Billings. The episode highlights how fear, political pressure, and shoddy police work combined to obscure the truth, leaving the real perpetrators unidentified. It also explores the multi-decade movement to right the injustice.

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Key Discussion Points & Insights

The Event: The Preparedness Day Bombing

• Setting the Scene
  • Dr. Joseph Moss, a Spanish-American War veteran and surgeon, marches in the 1916 parade supporting US involvement in WWI.
  • Amidst national debate over entering the war, the parade faces threats from isolationists ([00:39]).
  • Moss sees a smoking package fall from a rooftop, followed by an explosion ([01:20]).
  • The aftermath: "Through dust and smoke, Dr. Moss sees the vague shapes of men, women and children staggering in shock... In all, 10 people are killed and 40 others are wounded in this bombing, making it the deadliest act of terrorism in San Francisco's history." — Lindsey Graham ([01:45]).

The Investigation and Early Suspicions

• Tom Mooney as Target
  • Tom Mooney, labor activist and known radical, is followed and harassed by police before the bombing. On the day of the attack, he’s simply trying to get home, wanting to avoid confrontation ([05:51]).
  • "Protesting would only give the police what they want, an excuse to arrest Tom." — Lindsey Graham ([05:51]).
• Immediate Aftermath
  • Detective Martin Swanson quickly suspects Mooney and fellow radical Warren Billings, despite lack of direct evidence ([07:00]).
  • The Chamber of Commerce offers a $5,000 reward, drawing dubious witnesses:
    • An out-of-work waiter claims to have seen two men with a suitcase (who don’t match Mooney or Billings' description) ([07:50]).
    • An Oregon cattle rancher claims to see Mooney pass Billings a suitcase before the explosion ([08:10]).
• Arrests & Public Reaction
  • Billings is arrested; Mooney, away on a pre-planned vacation with his wife, returns to clear his name upon learning he is wanted ([08:40]).
  • Mooney faces a police force convinced of his guilt, a public eager for justice, and unreliable witnesses willing to say anything ([09:46]).
  • "A public crying out for revenge. And a witness who will say anything to see him hanged." — Lindsey Graham ([09:46]).

The Interrogation and Media Firestorm

• Police Tactics
  • Mooney is denied legal counsel, repeatedly interrogated and confronted by witnesses whose initial statements didn’t match his description ([12:56]).
  • "Tom repeats his request for legal representation. The police officers...ignore him." — Lindsey Graham ([12:56]).
• Evolving Witness Testimonies
  • The waiter changes his identification of Mooney after prompting from Swanson:
    • "As the waiter gazes at Tom in the cell, he changes his mind... 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." — Lindsay Graham ([13:45]).
• Media Frenzy and Impact on Justice
  • Newspapers run wild with speculation, fostering an assumption of guilt that taints the jury pool ([13:10]).
  • "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... It's all inaccurate or wildly speculative." — Lindsay Graham ([13:20]).

The Trial: Evidence vs. Public Opinion

• The Prosecution
  • The prosecution presents "charming" but false witness testimonies—most notably, the Oregon rancher, who wins over the jury ([14:35]).
  • The defense counters that Swanson has a vendetta and the prosecution is rushing to judgment, but the jury is unmoved ([15:38]).
• Mooney’s Photographic Alibi
  • Mooney is pictured at his apartment building minutes before the explosion; a clock in the photo offers a seemingly ironclad alibi ([16:05]).
  • Despite hard evidence, the jury believes the prosecution’s witnesses.
• Guilty Verdict
  • After six and a half hours of deliberation, Mooney is found guilty of first-degree murder; Billings is also convicted ([16:50]).
  • Quote: "But the jurors are more impressed by the charming rancher than a blurry photograph, and after six and a half hours of deliberation, they return with a guilty verdict." — Lindsay Graham ([16:50]).

The Final Outcome and Aftermath

• Sentencing and Campaign for Justice

  • Both Mooney and Billings are sentenced to death; public opinion is largely satisfied ([17:10]).
  • Over time, evidence unravels:
    • The rancher’s testimony is fabricated; he was 200 miles away at the time ([19:10]).
    • The waiter confesses that he was motivated by the reward ([19:32]).

• Political & Legal Obstacles

  • A federal commission, prompted by President Woodrow Wilson, reveals likely police framing ([19:06]).
  • Mooney’s sentence is commuted to life imprisonment just two weeks before his execution; a movement grows to win his release ([19:23]).
  • "Even with this new evidence, however, the governor of California was unwilling to release a man known to be a radical labor activist." — Lindsay Graham ([19:40]).

• Release and Legacy

  • After 22 years, Mooney is pardoned in 1939 by a new governor; greeted by over 200 vehicles of supporters as he leaves San Quentin ([19:59]).
  • Billings is released later that year, but Mooney dies just three years later at 62 ([20:40]).
  • Detective Swanson’s single-minded pursuit ends all further investigation into the real bombers.
  • Later historians point to followers of Luigi Galleani (Italian anarchists) as likely culprits, but "no definitive proof was ever found and it is still a mystery today precisely who was responsible" ([21:00]).

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Notable Quotes & Memorable Moments

• "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." — Lindsey Graham ([01:32])
• "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." — Lindsey Graham ([15:49])
• "Despite all the negative press and the false testimony from the prosecution's witnesses, Tom believes the photograph will clear his name. But the jurors are more impressed by the charming rancher than a blurry photograph." — Lindsey Graham ([16:46])
• “Detective Martin Swanson's vendetta against Tom distracted the police from any hope of finding the real perpetrators.” — Lindsey Graham ([20:45])
• “No definitive proof was ever found and it is still a mystery today precisely who was responsible for the bombing.” — Lindsey Graham ([21:00])

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Timestamps for Important Segments

• 00:39–02:25 — The Preparedness Day Parade and the bombing
• 05:51–07:00 — Detective Swanson sets his sights on Tom Mooney
• 08:10 — The dubious witness claims begin
• 09:46 — Mooney learns he’s wanted and decides to return to face justice
• 12:56–14:00 — The interrogation and manufactured witness testimony
• 14:35–16:05 — The trial, including the presentation of Mooney’s photographic alibi
• 16:50 — The verdict: guilty
• 19:06–21:00 — Federal review, campaign for justice, eventual release, and the unresolved questions

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Conclusion

This episode of History Daily powerfully recounts a tragic act of terrorism and a historic miscarriage of justice, illustrating how fear and public pressure, rather than facts, can shape legal outcomes. Despite the eventual recognition of Tom Mooney and Warren Billings’ innocence, the true perpetrators remain unidentified—casting a poignant light on the risks of prejudice and the perseverance required to undo a wrongful conviction.

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Next Episode Preview:
July 23, 1745 – An exiled prince lands in Scotland to ignite the last Jacobite rebellion.

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Credits:

• Hosted, edited, and executive produced by Lindsey Graham
• Written and researched by Owen Paul Nichols
• Audio & sound design team: Mohammad Shazi and Molly Bach
• Managing Producer: Emily Burke
• Executive Producers: William Simpson (Airship), Pascal Hughes (Noiser)

Transcript

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[Lindsey Graham]

It's 2pm on July 22, 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 a parade has been organized by San Francisco's Chamber of Commerce. The 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. Maass 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 US 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 Marcus 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 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, 10 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 23rd, 2nd, 1916. Hello History Daily listeners. The live show I've been telling you about for a few weeks has a new date, October 23rd at the Plaza Theater in Garland, Texas. This is my Days that Made America Tour, a thrilling evening of history, storytelling and music with me and a band live on stage. So if you're in the North Texas area or anywhere close, be sure to come out and see me live. More shows will be announced soon too, so for information on tickets and upcoming dates, go to historydailylive.com that's historydailylive.com Come see my days that Made America Tour live on stage. Go to historydailylive.com

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[Lindsey Graham]

From Noiser and Airship. I'm Lindsey 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 22, 1916, the Preparedness Day bombing. It's just after 1:30pm on July 22, 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 paradegoers 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 upstairs 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 had planned falls apart just a short while after they go upstairs. A bomb rips through the Preparedness day parade, killing 10 innocent bystanders and wounding 40 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 had 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 $5,000 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 Montesino, 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.

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It's 5am On July 26, 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, him, 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 and 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's 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 bomb, they would have 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 the cell, he changes his mind. He gives a nod to Detective Martin Swanson, who's standing beside him. And where 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 of 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. 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 is 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 as 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 experience 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's witnesses, Tom believes the photograph will clear his name. But the jurors are more impressed by the 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 re examined and a movement will emerge to save Tom Mooney's life.

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[Lindsey Graham]

It's January 7, 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-30s. Now he's closing in on 60. He suffers from jaundice and ulcers. He's lost half 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 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 Galliani 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 22, 1916. Next on History Daily, July 23, 1745. An exiled prince lands in Scotland to reclaim his family's lost throne and ignite the last Jacobite rebellion. From Noiser and Airship, this is History Daily Hosted, edited and executive produced by me, Lindsey Graham Audio editing by Mohammad Shazi Sound design by Molly Bach Supervising Sound Designer Matthew Phillips Music by Thrum this episode is written and researched by Owen Paul Nichols. Edited by William Simpson Managing Producer Emily Burke Executive producers are William Simpson for Airshift and Pascal Hughes for Noiser.