Galleani next moved to Switzerland, where he attended the University of Geneva before again being expelled as a dangerous agitator, this time for arranging a celebration in honor of the Haymarket rioters. He went back to Italy only to run afoul of the police again as a result of his anarchist activities. His return to Italy ended with his arrest for charges of conspiracy, where he spent five years in jail, exiled on the island of Pantelleria, off the coast of Sicily.
Escaping from Pantelleria in 1900, Galleani fled to Egypt; then, under threat of extradition, he fled to London; then, to the United States in 1901. He was 40 years old at this time, and a penniless immigrant.
Soon after arriving in the United States, Galleani attracted attention in radical anarchist circles as a charismatic orator who believed that violence was necessary to overthrow the 'capitalists' who oppressed the working man. He took undisguised pride in describing himself as a subversive, a revolutionary propagandist dedicated to subverting established government and institutions by disseminating a political philosophy based on direct action. By all accounts, Galleani was an extremely effective speaker and advocate of his policy of revolutionary violence. Carlo Buda, brother of Galleanist bombmaker Mario Buda, said of him, "You heard Galleani speak, and you were ready to shoot the first policeman you saw".
Galleani settled first in New Jersey, but was indicted for inciting a riot and fled to Canada (where he was quickly expelled). He then moved to Vermont, where he soon became known as a proponent of "propaganda by the deed". He was the founder and editor of Cronaca Sovversiva (Subversive Chronicle), an Italian anarchist newsletter which was published for 15 years before being shut down by the American government under the Sedition Act of 1918.
Subversive Chronicle usually consisted of no more than eight pages, and, at one point, had a claimed subscription of 5,000. It contained a variety of information considered essential to the Italian radical, including arguments on the nonexistence of God, the necessity of free love, tirades against both historical and recent government tyrannies as well as ignoble and overly passive Socialists. A frequent feature consisted of a list of addresses and detailed relationships of businessmen, 'capitalist spies', strikebreakers, and assorted enemies of the people. Most interesting was a small advertisement in later issues of the Chronicle that hawked a manual innocuously titled Health is in You!) for the sum of 25 cents, and described as a must-have for any proletarian family (Health Is In You! was in fact an explicit bomb-making manual). Several books that bear Galleani's name are actually excerpts from issues of Cronaca Sovversiva. The one exception is La Fine dell'anarchismo? (The End of Anarchism?) in which Galleani asserts that anarchy is far from dead, and still relevant as a political movement.
The activities of Galleani and his group centered around the promotion of a radical and violent form of anarchism, ostensibly by speeches, newsletters, labor agitation, political protests, and secret meetings. As time went on, however, many of Galleani's followers used bombs and other violent means to get their message across, a practice that Galleani actively encouraged, but in which he apparently never actually participated. With the assistance of a friend who was a chemist and explosives expert, Professor Ettore Molinari, Galleani authored a booklet covertly titled La Salute è in voi! (Health is in You!) a 46-page explicit 'how-to' on making a bomb. The foreword to the book clearly indicated its intent: to remedy the 'error' of advocating violence without giving subversives the physical means with which to destroy government officials and institutions. Galleani's handbook was characterized as accurate and practical by the New York City Bomb Squad, though an error Galleani made in transcribing Molinari's explosive formula for nitroglycerine resulted in one or more premature explosions when the bomb-makers failed to notice the mistake (Galleani thoughtfully provided a warning and corrected text to his readers in a 1908 issue of Cronaca Sovversiva).
Luigi Galleani's advocacy of violence is thought to have been first put into action by his followers in 1914. Galleanists were involved in at least two bombings in New York after police violently dispersed a protest at John D. Rockefeller's home in Tarrytown, New York. Over the next several months, bombings occurred in different areas of New York City, including police stations, churches, and courthouses. On November 14, 1914, a bomb was placed below the chair of Magistrate Campbell of the Tombs police court; it was discovered shortly before the judge was to ascend the bench (Campbell had sentenced a young anarchist for inciting to riot). In January 1915, police uncovered a plot to blow up St. Patrick's Cathedral in New York, and a copy of La Salute è in voi! was found in the house of one of the suspects.
One Chicago-based Galleanist, Nestor Dondoglio, a chef going by the name of Jean Crones, poisoned some 200 guests at a banquet in 1916 to honor Archbishop Mundelein by lacing the soup with arsenic. None of the guests died — in his eagerness to kill, Dondoglio had used too much poison, which prompted the victims to vomit it back up. Dondoglio's rooms were searched, turning up many phials of poison, but the poisoner himself was never apprehended. After leaving a series of taunts for police, Dondoglio fled for the East Coast, where he was hidden by other Galleanists until his death in 1932. On December 6, 1916, another Galleanist, Alfonso Fagotti, was arrested for stabbing a policeman with a butcher knife during a riot in Boston's North Square. In retaliation, the next day Galleanists exploded a bomb at the Salutation Street station of the Boston harbor police. Fagotti was later imprisoned, then deported to Italy.
Some authors have also suspected Galleanist participation in the 1916 Preparedness Day bombing in San Francisco. Though never indicted or convicted of involvement in the attack, some historians have noted that the Preparedness Day time bomb (a suitcase packed with a clockwork timer, blasting caps, dynamite, and cast-iron sash weights to increase casualties) had become a component of Galleanist bomb attacks, in particular the work of Mario Buda.
In 1917, at Galleani's urging, many Galleanists left the United States for Mexico to await the coming of the Revolution and escape registration for the draft. The bombings ceased - for a time. In late 1917, disillusioned at the failure of the Revolution and by living conditions in Mexico, many of the Galleanist exiles returned to the U.S. and resumed their work.
On November 24, 1917, in the city of Milwaukee, Mario Buda is thought to have constructed a large black powder bomb with an acid "delay" detonator that exploded at a Milwaukee police station where it had been transported after its discovery in a church basement. The blast killed nine policemen and a female civilian, at the time the worst incident of terrorist violence in the United States. There were scattered incidents of successful and unsuccessful bombings in New York City, San Francisco, Washington, D.C., Boston, and Milwaukee, which were attributed to adherents of Galleani, but again, no criminal prosecutions followed. By this time, Congress and the public at large had begun to demand action against militant anarchists and other advocates of physical violence.
A 19-year-old female Galleanist, Gabriella Segata Antolini, was arrested January 17, 1918 for transporting a satchel filled with dynamite she had received from Carlo Valdinoci on a Chicago-bound train. When questioned, she provided a false name and refused to cooperate with the authorities or supply them with any information; she was sent to prison for fourteen months before being released. While in prison, Antolini met noted anarchist Emma Goldman, with whom she became friends. Galleani himself was arrested several times for inciting labor unrest and advocating anarchy, but was always acquitted.
In February 1918, U.S. authorities raided the offices of Cronaca Sovversiva, suppressed publication, and arrested its editors. The publication's subscription list had been hidden by a staff member, but authorities obtained more than 3,000 names and addresses of subscribers from a forthcoming issue that had been bundled for mailing.
In October 1918, Congress passed a new law aimed at resident aliens involved in either anarchism or revolutionary political organizations, the Anarchist Exclusion Act. In response, Galleani and his followers declared war on the U.S. government and announced their intentions through a published flyer: Deportation will not stop the storm from reaching these shores. The storm is within and very soon will leap and crash and annihilate you in blood and fire...We will dynamite you! A series of bombings of prominent businessmen and officials followed, including a bomb that went off at the home of Judge von Moschzisker, who back in 1908 had sentenced four Italian anarchists to long terms of imprisonment.
On February 27, 1919, the day after hearing an incendiary speech by Galleani (who was awaiting his deportation notice), four Galleanists died when a dynamite bomb they were planting in a Franklin, Massachusetts textile mill exploded prematurely in their faces.
In late April 1919, approximately 30 dynamite package bombs destined for a wide cross-section of prominent politicians, justice officials, and financiers (including John D. Rockefeller) were sent through the mail. One bomb was even addressed to a lowly FBI agent, who just happened to be assigned to find several Galleanist fugitives, including Carlo Valdinoci. The Galleanists intended their bombs to be delivered on May Day, the international day of communist, anarchist, and socialist revolutionary solidarity. Only a few of the packages were delivered. Because the plotters had neglected to add sufficient postage, one of the packages was discovered, and its distinctive markings enabled interceptions of most of them. No one was killed by the mail bombs that were delivered, but when a house servant for Senator Hardwick (a sponsor of the Anarchist Act) opened the package sent to his home in Georgia, her hands were blown off.
In June 1919, the Galleanists managed to blow up eight large bombs nearly simultaneously in several different U.S. cities. The targets included the homes of judges, businessmen, a mayor, an immigration inspector, and a church. Apparently believing their first bombs were insufficiently powerful, the new bombs used up to twenty pounds of dynamite wrapped with metal shrapnel. Among the intended victims were politicians who had endorsed anti-sedition laws and deportation, or judges who had sentenced Galleanist anarchists to prison. The homes of Mayor Harry L. Davis of Cleveland, Judge W.H.S. Thompson, Massachusetts State Representative Leland Powers, and Attorney General A. Mitchell Palmer (already a previous target of a Galleanist mail bomb), were all attacked. None of the high officials were killed, but the bombs did claim the lives of a night watchman, a woman who had been passing by one of the victim's homes, and one of the Galleanists - Carlo Valdinoci, a former editor of Cronaca Sovversiva, and a close associate of Galleani himself. Though not injured, Palmer and his family were thoroughly shaken by the blast.
Valdinoci was blown to bits in front of Palmer's house, which was largely destroyed (the powerful blast hurled several neighbors from their beds in nearby homes). Valdinoci either tripped over his bomb, or it went off prematurely as he was placing it on Palmer's porch. The police collected Valdinoci's remains over a two-block area, and his hair and scalp were found on the roof across the street. All of the bombs were delivered with a flyer, titled Plain Words, that warned: 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.
Andrea Salsedo, a typesetter and Roberto Elia, a compositor were arrested by authorities after one of the flyers left with a bomb package was traced to a printing shop where Salsedo worked. Salsedo was questioned intensively (some say tortured) by federal agents, but after providing some information, became increasingly distraught. He died after jumping or being pushed out of the 14th-story building where he was being held. Although Salsedo admitted he was an anarchist and to printing the bomb flyer, no other arrests or convictions in the bombings followed, due to lack of evidence and refusal of other Galleanists to provide information to the authorities. Elia was later deported; according to his lawyer, he turned down an offer to allow him to remain in the United States if he could deny his connection to the Galleanists.
After Valdinoci's death, Ferrucio Coacci and Nicola Recchi appear to have taken a more prominent role of leadership of the group; both were bombmakers. Galleanist bombmaker Nicola Recchi had his left hand blown off by a premature explosion, but kept on making bombs anyway.
Under previous laws, Attorney General Palmer's Justice Department did not have the authority to deport resident aliens; only the Immigration Department could do so. Up to that point, accused anarchists could and did delay their deportations with continual legal appeals. With the public and the press clamoring for action, Palmer and other government officials began a series of investigations, using warrantless wiretaps, reviews of subscription records to radical publications, and other measures to investigate thousands of anarchists, communists, and other radicals. With evidence in hand, and after agreement with the Immigration Department, Palmer and the Justice Department began rounding up and deporting as many radicals as they could under the Anarchist Act – a wave of arrests and deportations known as the Palmer Raids.
After their return to Italy, Ferrucio Coacci and Nicola Recchi later moved to Argentina, where Coacci promptly joined forces with the violent Argentine anarchist, Severino Di Giovanni. Deported from Argentina after Giovanni's execution, Coacci returned there after World War II. Mario Buda also returned to Italy shortly after the Wall Street bombing, where he lived until his death in 1963.