Pontiac's Rebellion, 1763
Library of Congress

Pontiac's Rebellion, 1763
May 7, 1763: Early History

British soldiers, besieged by American Indian tribes during Pontiac’s Rebellion, give blankets infected with the smallpox virus to tribal representatives.

February 10, 1882

Paul Fildes, son of noted painter Samuel Fildes, is born in London.

June 25, 1892

Shiro Ishii is born near Tokyo.

September 20, 1895

Ira Baldwin is born on an Indiana farm.


Fildes enters medical school to study to become a surgeon, but soon transfers to bacteriology.


Guards patrol the gates at Porton Down Germ Warfare establishment. The British establish a secret facility at Porton Down to deal with the threat of chemical weapons.


Ishii receives his medical degree from Kyoto Imperial University; he soon develops an interest in bacteriology.

June 17, 1925: Geneva Protocol

Spurred by the horrors of World War I, delegates in Switzerland create a Geneva Protocol banning the use of chemical and bacteriological methods of warfare. However, countries are still allowed to research, develop, and produce these weapons. Thirty-nine countries sign the protocol, including the United States. Although the Senate refuses to ratify the treaty, the U.S. government says it will still abide by the terms.


Spurred by his interest in biological weapons, Ishii begins a two-year fact-finding trip around the world, visiting Europe and America.


Shiro Ishii is appointed professor of immunology at the Tokyo Army Medical College. He is promoted to the rank of major in Japan’s Army Medical Corps and begins to advocate for a Japanese biological weapons program.


Fildes edits a nine-volume treatise on bacteriology that is published by the Medical Research Council, whose Bacteriological Chemistry Unit he heads.


The Japanese Army gives Shiro Ishii control of three biological research centers, including one in Manchuria, a Chinese province that the Japanese had invaded a year earlier.

March 1933

U.S. Army Medical Corps Major Leon Fox publishes an article in the magazine Military Surgeon dismissing the idea of biological weapons. "Practically insurmountable difficulties prevent the use of biologic agents as effective weapons," Fox writes.

1934: International Biological Weapons Research

Great Britain begins taking steps towards establishing its own biological weapons research project. Although the Medical Research Council is cool to the idea, Fildes agrees to assist the government.


Construction commences on a large Japanese biological weapons complex called Ping Fan near the Manchurian city of Harbin.

Nazi Invasion of Poland, 1939
Library of Congress

Nazi Invasion of Poland, 1939
September 1, 1939

World War II begins in Europe with the invasion of Poland by Nazi Germany.

September 19, 1939

In a speech, German Chancellor Adolf Hitler boasts of fearsome German weapons against which his enemies would be defenseless. This fuels speculations among Allied leaders about what weapons German scientists may be developing.


The Japanese biological weapons complex Ping Fan begins operations. It employs some 3,000 personnel under Ishii's direction, working on a wide variety of biological agents, including bacteria that cause plague and anthrax. Over the next five years, Unit 731, as it becomes known, conducts horrific tests on Chinese prisoners and, allegedly, some Allied POWs. Victims are injected with, forced to eat, and made to breathe deadly pathogens. Often prisoners are killed before the diseases have become terminal so autopsies can be performed. Ishii's men also create bacteriological bombs, and later that year Japanese warplanes repeatedly drop porcelain bombs containing fleas infected with plague over Chinese towns, resulting in several outbreaks of plague among the human population.

Meanwhile, in England, a new biology department is established at Porton Down with Fildes as its head. His initial research focuses on botulism and anthrax.

November 18, 1941

A committee of nine eminent American biologists convenes at Secretary of War Henry Stimson's request to investigate the possibility of germ warfare.

December 7, 1941: America Joins the War

The Japanese attack Pearl Harbor, bringing America into the war. That same day, British Prime Minister Winston Churchill receives a top-secret memo summarizing developments at Porton Down and reporting that cattle cakes laced with anthrax bacteria are the only biological weapons that currently can be deployed.

January 2, 1942

Churchill’s Defense Committee meets and gives the go-ahead for production of these cattle cakes. Later that year, the first of some five million cattle cakes are manufactured at Porton Down. The plan, named, “Operation Vegetarian,” is to drop them from aircraft over Germany in the hope of wiping out its cattle. This plan is never implemented.

February 17, 1942

Stimson's committee issues the first of its two reports, concluding that biological warfare is "distinctly feasible" and the United States should begin its own biological weapons program immediately.

April 29, 1942

Stimson writes to President Franklin Roosevelt conceding that biological warfare is "a dirty business" but arguing America must be prepared. In May, Roosevelt approves the creation of a U.S. biological weapons program.

May 27, 1942

British-trained commandoes ambush high-ranking Nazi leader Reinhard Heydrich near Prague. Although he suffers only minor wounds, Heydrich will die suddenly a week later. Fildes later claims to have "had a hand" in the assassination, perhaps by supplying the commandoes with grenades contaminated with botulinum toxin.

June-July 1942

The Japanese test Salmonella on Chinese prisoners. Then they disperse the bacteria that cause typhoid, cholera, and other food-borne diseases over Chinese populations.

July 15, 1942: Anthrax Tests Successful

A team of Porton Down scientists led by Fildes begin outdoor testing of anthrax bacteria on the remote Scottish island of Gruinard. They set off anthrax-filled bombs and observe their impact on a group of sheep placed downwind. Most of the sheep die within a few days.

September 26, 1942

Fildes' team has an anthrax bacteria bomb dropped from an airplane onto Gruinard. Although it lodges in a bog and does not infect any sheep, a similar test is more successfully repeated a month later on a beach in Wales.

November 1942

Fildes arrives in Washington to meet with officials. Recognizing U.S. superiority in mass production, he asks for American help in making biological weapons. Fildes' first request is for seven pounds of botulinum toxin (code named "Agent X"), which is a proteinaceous substance produced by the bacterium Clostridium botulinum. Later that month, Ira Baldwin, now a professor and head of the bacteriology department at the University of Wisconsin, receives a call from Colonel William Kabrich of the U.S. Army Chemical Warfare Service. Kabrich asks Baldwin to attend a meeting at the National Academy of Sciences in Washington. Once there, Baldwin and other scientists are sworn to secrecy and then asked whether they believe that the U.S. can produce mass quantities of biological agents. Baldwin says yes, and 10 days later Kabrich asks him to head up the program.

December 21, 1942

Baldwin arrives in Maryland and becomes scientific director and administrator of the U.S. Army's biological warfare research program. He soon begins recruiting colleagues from University of Wisconsin to join him.

January 19, 1943: U.S. Involvement Grows

Baldwin visits Horn Island, off the Mississippi coast, and will select it as a place to conduct outdoor biological tests.

Fort Detrick research personnel
Fort Detrick Public Affairs Office and the Detrick Center for Training and Education Excellence

Fort Detrick research personnel
February 1943

Baldwin locates a site for his work at a little-used National Guard airfield in Frederick, Maryland, that becomes known as Camp Detrick. The Army officially takes it over in March and staff members begin arriving in April. The Army also acquires Horn Island, ret research. Scientists completed interior equipment intstallation; the boiler was operated by Alex Bryant, then a soldier.

Atomic bomb rises over Nagasaki, Japan
National Archives and Records Administration

Atomic bomb rises over Nagasaki, Japan
May 1943

Workers erect a two-story building dubbed “Black Maria” at Camp Detrick. The next month, a group of scientists led by Harvard bacteriologist Alwin Pappenheimer begin work there on filling Fildes’ request for seven pounds of Clostridium botulinum. Within two months, they have succeeded. Later that year, construction begins on two pilot plants for larger-scale production of biological agents.

July 1943

Camp Detrick scientists begin outdoor biological bomb testing, using yeast instead of pathogens for the initial trial runs.

Gruinard after being bombed with Anthrax
AP/Wideworld Photos: Martin Cleaver

Gruinard after being bombed with Anthrax
August 1943

The British conduct more anthrax bomb tests at Gruinard.

October 28, 1943

Testing of bombs containing botulinum toxin begins at Horn Island and continues for nine months. The tests lead the Army to conclude that such biological weapons are unlikely to be effective.

March 8, 1944

Convinced that the Germans will use biological weapons if able to produce them and that the British must be able to retaliate in kind, Churchill places an order for 500,000 "anthrax" bombs, i.e., bombs containing anthrax bacterial spores, with the Americans.

May 1944: Anthrax at the Ready

Camp Detrick produces a first batch of 5,000 anthrax bombs for the British, but it is clear that filling the whole order (plus another 500,000 bombs for American use) exceeds its capacities. The Americans decide to construct a new production facility near Vigo, Indiana, and begin safety testing there that summer.

August 1945

In Manchuria, Unit 731 is blown up ahead of the advancing Russian Army, destroying most but not all records of Ishii's activities.

August 13, 1945

The Army closes the Horn Island site, declaring it in “excess.” The Vigo production plant, still in safety tests, has manufactured four tons of an anthrax bacterium simulant, but nothing that could actually be used as a biological weapon.

September 2, 1945: The Atomic Bomb and the End of WWII

Japan officially surrenders to the United States after atomic bombs are dropped on Hiroshima and Nagasaki, ending World War II.

September 3, 1945

A committee is formed to oversee the demobilization of the Vigo plant. Later that month, the Camp Detrick administration begins slashing work schedules and Baldwin heads back to Wisconsin. Meanwhile, a Camp Detrick scientist named Murray Sanders arrives in Japan to pursue reports of a Japanese biological weapons program.

October 9, 1945

Sanders begins interrogating Tomosada Masuda, a colleague of Ishii's at the Ping Fan facility.

November 10, 1945

The mayor of Ishii's hometown announces his death; the funeral takes place a few days later.

December 3, 1945

A confidential U.S. intelligence report suggests Ishii is not, in fact, dead, but has gone into hiding.

January 3, 1946

The U.S. War Department releases a report on the nation's wartime biological weapons program, keeping many key details obscure.

January 9, 1946: A Deal with Ishii

The U.S. demands that the Japanese government produce Ishii, who is in fact alive; he is handed over to American forces eight days later.

January 22, 1946

Another Camp Detrick operative, Lieutenant Colonel Arvo Thompson, begins interrogating Ishii, who lies repeatedly about his wartime activities. Thompson does not press him, but returns to America and writes up a report.

April 15, 1947

A third investigator from Camp Detrick, Norbert Fell, arrives in Japan. War crimes trials are about to be held, and the Soviets have shown interest in Ishii. Fell and his colleagues therefore think Ishii may now be more cooperative.

May 5, 1947

General Douglas MacArthur sends a request by radio to the State-War-Navy Coordinating Committee in Washington, D.C. for documentary immunity for Shiro Ishii and his colleagues and urges them to grant it. He writes "information about vivisection useful."

May 8, 1947

Ishii tells Fell that he is willing to share what he knows, including details of his human experiments, in exchange for immunity from prosecution. Hopeful of gathering useful information, the Americans agree and even coach Ishii on how to avoid questioning by the Soviets. Although Ishii's information is eventually judged to be of little worth, the U.S. honors its immunity deal and no mention is made of biological weapons at the Japanese war crimes trials.

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