Campus Alert Archive
UW-Madison

A Ton of Ammonium Nitrate at 3:42 AM: The Sterling Hall Bombing

WIotheradvisorymedium confidence
Confirmed Threat

At 3:42 AM CDT on August 24, 1970, four anti-Vietnam War radicals — Karleton Armstrong, Dwight Armstrong, David Fine, and Leo Burt — detonated a stolen Ford Econoline van loaded with approximately 2,000 pounds of ammonium nitrate-fuel oil explosive outside Sterling Hall on the University of Wisconsin-Madison campus, intending to destroy the U.S. Army Mathematics Research Center on the building's upper floors. The blast killed 33-year-old physics postdoctoral researcher Robert Fassnacht, who was working in the basement on a vacation deadline, and injured three others. The explosion was heard 30 miles away, shattered windows for blocks, and left an 8-foot-deep crater on Charter Street.

Alerts
3
Response
—
Killed
1
Injured
3
Institution
University of Wisconsin-Madison
Public R1 · WI
~35,000 students
Confirmed Timeline

Alert Sequence

3 messages in sequence

Some alert texts below are approximate reconstructions from news coverage, not confirmed verbatim transcripts. Reconstructed texts are shown in italic with a dashed border. Verified verbatim texts have a solid border and are marked accordingly.

INITIAL ALERTPhone
Approximate reconstructionSterling Hall bombing - Wikipedia (transcribed from Madison Police dispatch logs and FBI records)247 chars
Okay pig listen and listen good. There is a bomb at the Army Math Research Center, University. It is going up in five minutes. Get everyone out of there, clear the area, warn the hospital. I am not bullshitting, Mac. Get everyone out of there now.

This text has been reconstructed from news coverage and may not reflect the exact original wording.

David Fine placed the warning call to the Madison Police dispatcher at approximately 3:39 AM CDT on August 24, 1970, three minutes before detonation
The verbatim text is transcribed from Madison Police dispatch logs and FBI records as reconstructed in published accounts; the exact wording differs slightly across sources
Madison Police did not have time to clear Sterling Hall in three minutes; Robert Fassnacht was working in the basement and never received any warning
There was no campus-wide notification system at UW-Madison in 1970 capable of warning building occupants in three minutes — the only mechanism was the Madison Police dispatcher relaying to whatever security personnel happened to be on duty
UPDATESiren+3 min
Approximate reconstruction427 chars
[At 3:42 AM CDT on August 24, 1970, the bomb detonated. The blast was heard 30 miles away. Sterling Hall's east wing was largely destroyed; windows shattered for blocks in every direction; an 8-foot-deep crater was left on Charter Street. Madison Fire Department and Madison Police converged within minutes, summoned by the explosion itself rather than by any campus alert. Sterling Hall was evacuated by emergency responders.]

This text has been reconstructed from news coverage and may not reflect the exact original wording.

The detonation occurred at exactly 3:42 AM CDT — approximately three minutes after David Fine's warning call, but minutes were not enough time to evacuate even one floor of the six-story building
Robert Fassnacht had gone to his basement laboratory the night of August 23 to finish a low-temperature physics experiment before leaving on a family vacation; he was killed instantly by the blast wave
The explosion damaged 26 buildings on the UW-Madison campus and shattered glass throughout central Madison; Sterling Hall was deemed structurally salvageable but the east wing was demolished and rebuilt
FOLLOW-UPPhone
Approximate reconstruction557 chars
[The Federal Bureau of Investigation took control of the bombing investigation by mid-morning August 24, 1970. Sterling Hall was sealed as a crime scene. The Army Mathematics Research Center had been on the second, third, and fourth floors and suffered significant damage but no Army personnel were injured because the building was empty at 3:42 AM. UW-Madison Chancellor H. Edwin Young announced the death of Robert Fassnacht and the launch of a federal investigation by midday. The notification of Fassnacht's family was made by Madison Police in person.]

This text has been reconstructed from news coverage and may not reflect the exact original wording.

The FBI eventually identified the four bombers — Karleton Armstrong, Dwight Armstrong, David Fine, and Leo Burt — within weeks; the Armstrong brothers and Fine were captured in subsequent years
Leo Burt has never been found and remains on the FBI's list of fugitives; periodic reported sightings have not led to capture
Robert Fassnacht left behind his wife Stephanie and three young children, including 3-year-old twins; the Fassnacht family quietly sought the abolition of the Army Mathematics Research Center after his death
There was no campus-wide alert system at UW-Madison in 1970; news of the bombing reached students by radio (WHA), television (WMTV, WISC-TV), and through phone trees
Context

Background

The Sterling Hall bombing at the University of Wisconsin-Madison was the most destructive act of domestic terrorism on a U.S. college campus until the 1995 Oklahoma City bombing. At 3:42 AM CDT on August 24, 1970, four anti-Vietnam War radicals — calling themselves the New Year's Gang — detonated a stolen Ford Econoline van loaded with approximately 2,000 pounds of ammonium nitrate-fuel oil (ANFO) explosive outside Sterling Hall, the physics building that housed the U.S. Army Mathematics Research Center on its upper floors. The bombers were Karleton Armstrong, his younger brother Dwight Armstrong, David Fine, and Leo Burt. About three minutes before detonation, David Fine placed a warning call) to the Madison Police dispatcher demanding that 'the Army Math Research Center' be cleared. Three minutes was not enough time. The blast was heard 30 miles away; it shattered windows for blocks; it left an 8-foot crater on Charter Street; and it killed 33-year-old postdoctoral physics researcher Robert Fassnacht, who was working alone in his basement laboratory finishing a low-temperature physics experiment so he could leave on a family vacation. Three other people were injured. The Armstrong brothers, Fine, and Burt all fled to Canada in the days after the bombing. Karleton Armstrong was captured in Toronto in February 1972 and sentenced to 23 years; David Fine was captured in San Rafael, California, in January 1976 and served three years; Dwight Armstrong was captured in Toronto in 1977 and served seven years. Leo Burt has never been apprehended and remains on the FBI's list of fugitives. The bombing is widely cited as the moment the radical anti-war movement crossed a moral line it could not retreat from; the death of a non-combatant scientist with three young children at home shattered the New Left's claim to nonviolence. The case is included in this archive because it pre-dates the Clery Act by 20 years and demonstrates the impossibility of a meaningful campus alert in an era when the only notification mechanism between a phoned-in warning and a 2,000-pound bomb was a single police dispatcher with a switchboard.
Analysis

Key Findings

The Sterling Hall bombing was the deadliest act of campus political violence in 20th-century American history and the most destructive bombing on a U.S. college campus until Oklahoma City in 1995
David Fine's warning call came approximately three minutes before detonation — far too short an interval to evacuate even one floor of Sterling Hall
Robert Fassnacht, 33, was a physics postdoc with no connection to the Army Mathematics Research Center on the upper floors; he was working alone in the basement on his own research
Three of the four bombers were eventually captured; Leo Burt remains an FBI fugitive 55 years later
The bombing pre-dates the Clery Act by 20 years; UW-Madison had no campus-wide alert system capable of warning Sterling Hall occupants in 2 minutes
Outcome
One killed: Robert Fassnacht, 33, postdoctoral physics researcher. Three injured: Paul Quin, David Schuster, and Norbert Sutler. The Army Mathematics Research Center on the second through fourth floors of Sterling Hall was largely destroyed. Three of the four bombers were eventually captured: Karleton Armstrong (1972, sentenced to 23 years, served 7), Dwight Armstrong (1977, sentenced to 7 years), and David Fine (1976, sentenced to 7 years, served 3). Leo Burt has never been found and remains an FBI fugitive. The bombing dramatically altered the trajectory of the New Left and is widely cited as the act that broke the back of the radical anti-war movement.
Provenance

Sources

  1. Source
    Sterling Hall bombing - Wikipedia
    en.wikipedia.org
  2. Official
    Sterling Hall Bombing of 1970 - UW Archives and Records Management, UW-Madison Libraries
    library.wisc.edu
  3. Official
    When bomb tore through Sterling Hall 50 years ago, he was inside - UW-Madison News
    news.wisc.edu
  4. Source
    The Blast That Changed Everything - On Wisconsin Magazine
    onwisconsin.uwalumni.com
  5. News
    What To Know About the Sterling Hall Bombing - City Cast Madison
    madison.citycast.fm
  6. News
    Newly released FBI files give details of 1970 Sterling Hall bombing aftermath - Wisconsin State Journal
    madison.com
Tags
bombingdomestic-terrorismanti-war-protest1970spre-clerypre-modern-alertingwisconsincasualtiesfbi-fugitivevietnam-erahistoricaltwo-minute-warning
Added May 2026Updated May 2026Via ingestion