The Palmer Raids were a series of controversial raids by the United States Department of Justice and Immigration and Naturalization Service from 1919 to 1921 on suspected radical leftists in the United States. The raids are named for Alexander Mitchell Palmer, United States Attorney General under Woodrow Wilson.
The crackdown on radical left-wing political groups had actually begun during World War I. After a series of bomb attacks of court buildings, police stations, churches and homes attributed to violent immigrant anarchist groups, the Department of Justice and its small Bureau of Investigation (BOI) (predecessor to the FBI) had begun to track their activities with the approval of President Woodrow Wilson.
In 1915, Wilson warned of:
Hyphenated Americans (who) have poured the poison of disloyalty into the very arteries of our national life. Such creatures of passion, disloyalty and anarchy must be crushed out.
Handicapped by the secrecy of these groups and limited Federal law enforcement capabilities, the Bureau of Investigation significantly increased its workload on anarchist movements after 1917 when the Galleanists (followers of Luigi Galleani) and other radical groups commenced a new series of bomb attacks in several major American cities. The Russian Revolution of 1917 was also a background factor: many anarchists believed that the worker's revolution there would quickly spread across Europe and the United States.
On June 15, 1917, Congress passed the Espionage Act. The law set punishments for acts of interference in foreign policy and espionage. The act authorized stiff fines and prison terms of up to 20 years for anyone who obstructed the military draft or encouraged "disloyalty" against the U.S. government. After two anarchist radicals, Emma Goldman and Alexander Berkman, continued to advocate against conscription, Goldman's offices at Mother Earth were thoroughly searched, and volumes of files and detailed subscription lists from Mother Earth, along with Berkman's journal The Blast, were seized. As a Justice Department news release reported:
A wagon load of anarchist records and propaganda material was seized, and included in the lot is what is believed to be a complete registry of anarchy's friends in the United States. A splendidly kept card index was found, which the Federal agents believe will greatly simplify their task of identifying persons mentioned in the various record books and papers. The subscription lists of Mother Earth and The Blast, which contain 10,000 names, were also seized.
Congress also passed a series of immigration, anti-anarchist, and sedition acts (including the Sedition Act of 1918 and the Anarchist Exclusion Act) that sought to either criminalize or punish (through deportation) advocacy of the violent overthrow of the government or desertion from the armed forces, defiance of the draft, or membership in anarchist or revolutionary organizations.
In 1919, the U.S. House of Representatives refused to seat Socialist representative Victor L. Berger from Wisconsin because of his socialism, German ancestry, and anti-war views.
On June 2, 1919, several bombs were detonated by Galleanist anarchists in eight American cities, including one in Washington, D.C., that damaged the home of newly appointed Attorney General A. Mitchell Palmer. The same bomb detonated near Franklin Roosevelt who lived across the street and was walking home with his wife. Palmer was badly shaken up (the bomber, Carlo Valdonoci, was killed by the bomb, which exploded prematurely). All of the bombs were delivered with a flyer reading:
War, Class war, and you were the first to wage it under the cover of the powerful institutions you call order, in the darkness of your laws. There will have to be bloodshed; we will not dodge; there will have to be murder: we will kill, because it is necessary; there will have to be destruction; we will destroy to rid the world of your tyrannical institutions.
Palmer, twice the intended victim of assassination, had a personal as well as public motivation to win the battle against the radical left and those preaching violence.  After his close calls at the hands of the Galleanists, he appears to have grouped all those identified with the radical left as enemies of the United States. He stated his belief that Communism was "eating its way into the homes of the American workman," and that socialists were responsible for most of the country's social problems.
Calls from the press and a worried public quickly escalated for the federal government to take action against those perpetrating the violence. Pressure to take action intensified after anarchists, communists and other radical groups called on draft-age males to refuse conscription and/or registration for the army, and for troops already serving to desert the armed forces. President Wilson ordered Attorney General Palmer to take action.
At the time, Emma Goldman, Alexander Berkman, and Luigi Galleani were in the forefront of the anti-conscription movement. Valdonoci, the Palmer house bomber, was later identified as a militant follower of Luigi Galleani. Attorney General Palmer requested and received a massive supplementary increase in Congressional appropriations in order to put a stop to the violence. Palmer then ordered the Department of Justice and the Bureau of Investigation to prepare for what would become known as the Palmer Raids.
In 1919, J. Edgar Hoover was put in charge of a new division of the Justice Department's Bureau of Investigation, the General Intelligence Division. By October 1919, Hoover's division had collected 150,000 names in a rapidly expanding index. Using this information, starting on November 7, 1919, BOI agents, together with local police, orchestrated a series of well-publicized raids against suspected radicals and foreigners, using the Espionage Act of 1917 and the Sedition Act of 1918. Palmer and his agents were accused of using torture and other controversial methods of obtaining intelligence and collecting evidence on radicals, including informers and wiretaps.
Victor L. Berger was sentenced to 20 years in prison on a charge of sedition, although the Supreme Court of the United States later overturned that conviction. The radical anarchist Luigi Galleani and eight of his Galleanist adherents were deported in June 1919 under the provisons of the Anarchist Exclusion Act, three weeks after the June 2 wave of bombings. Although authorities did not have enough evidence to arrest Galleani for the bombings, they could deport him because he was a resident alien who had overtly encouraged the violent overthrow of the government, was a known associate of Carlo Valdonoci and had authored an explicit how-to bomb making manual titled La Salute é in Voi (The Health is Within You), used by other Galleanists to construct some of their package bombs.
In December 1919, Palmer's agents gathered 249 people of Russian origin, including well-known radical leaders such as Emma Goldman and Alexander Berkman, and placed them on a ship bound for the Soviet Union (The Buford, called the Soviet Ark by the press). In January 1920, another 6,000 were arrested, mostly members of the Industrial Workers of the World union. During one of the raids, more than 4,000 individuals were rounded up in a single night. By January 1920, Palmer and the Department of Justice had organized the largest mass arrests in U.S. history, rounding up at least 10,000 individuals.
Louis Freeland Post, then Assistant Secretary of Labor,  cancelled more than 2000 of these warrants as being illegal. Of the many thousands arrested, 556 people were eventually deported under the 1918 Anarchist Act.
For most of 1919 and early 1920, much of the public sided with Palmer, but this soon changed. Palmer announced that an attempted Communist revolution was certain to take place in the U.S. on May 1, 1920 (May Day). No such revolution took place on May 1, leading to criticism of Palmer. However, on September 16 of that year the Wall Street bombing by Galleanist anarchists killed thirty-eight persons and wounded 400; it was the deadliest bombing attack to date in the United States.
On May 28, 1920, the American Civil Liberties Union published a report entitled Report of the Illegal Practices of the United States Department of Justice which carefully documented unlawful Departmental authorization of the arrests of suspected radicals, illegal entrapment by agent provocateurs and unlawful incommunicado detention. The report was signed by prominent lawyers and law professors, including Felix Frankfurter, Roscoe Pound and Ernst Freund. Palmer was called before the House Rules Committee and strongly defended his actions and that of his department, saying "I apologize for nothing that the Department of Justice has done in this matter. I glory in it."
In June 1920, Judge George Anderson effectively ended the raids when he ordered the discharge of twenty aliens, and denounced Department of Justice actions. The discovery of trumped-up charges and the Daugherty-Burns scandal turned public opinion against further large-scale arrests and searches, though subsequent bomb attacks and public clamor to punish the radicals believed responsible did not subside. Palmer, once seen as a likely presidential candidate, lost the nomination. For their part, the Galleanists continued their violent bombing campaign, which would last another twelve years.
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Manning, Lona, 9/16/20: Terrorists Bomb Wall Street, Crime Magazine, January 15, 2006
Hill, Robert A. Compiler and Editor, The FBI's RACON: Racial Conditions in the United States during World War I. Ithaca, N. Y.: Northeastern University Press (May 1, 1995). ISBN 1-55553-227-6.
Kornweibel, Theodore, Jr. "Investigate Everything": Federal Efforts to Compel Black Loyalty During World War I. 416 pages. Indiana University Press (May 1, 2002). ISBN 0-253-34009-8.
Kornweibel, Theodore, Jr. Seeing Red: Federal Campaigns Against Black Militancy, 1919-1925 Blacks in the Diaspora Series. 248 pages. Indiana University Press (December 1, 1999). ISBN 0-253-21354-1.
McCormick, Charles H., Hopeless Cases: The Hunt for the Red Scare Terrorist Bombers, University Press of America (2005), ISBN 0761831339, 9780761831334