New York is no stranger to explosives. Over the past century the city has endured bombings carried out by lunatics, extortionists, and extremists of all stripes. In the first decade of the 20^th century, the criminal organization known as the Black Hand terrorized successful Italian immigrants, bombing their homes and shops if they did not pay protection money. In 1904, the NYPD founded the Italian Squad under Lieutenant Joseph Petrosino to combat this evil. This was the genesis of the Bomb Squad.

The city was and continues to be a battleground for political strife. For a hundred years, groups espousing a range of radical causes or special interest grievances have targeted sites in New York in their quest for justice, or revenge. Broadly speaking, we can identify three periods of terrorist activity in the city: the 1910s, with anarchists and labor radicals attacking symbols of capitalism; the 1960s and 1970s, when young self-styled revolutionaries and black radicals assaulted the establishment, and ethnic and racial pride stirred others to commit acts of terror; and the attacks by adherents of radical Islam since the 1990s, a conflict that offers no end.

What each has in common is that youth—with few exceptions terrorists are young—embraced an ideology and carried it to its illogical end. If the cause is just, then any actions can be justified, or in the words of Malcolm X, “by any means necessary.” I much prefer the words of Ralph Waldo Emerson—“the ends preexist in the means.”

The first age of terror lasted but a few years, and the anarchists detonated very few bombs, but the state saw in them a great threat. After all, an anarchist had assassinated President William McKinley in 1901. One group of anarchists blew themselves up in a Manhattan tenement on July 4, 1914 while assembling a bomb intended for John D. Rockefeller. Members of the International Workers of the World exploded a bomb in St. Patrick’s Cathedral and another in the courtroom of the judge presiding over the trial of I.W.W. members. An undercover officer infiltrated the group brought about their arrest. How did they expect planting bombs in a church would advance their cause?

The most dramatic incident was the still unsolved bombing outside the headquarters of the J.P. Morgan Company at 23 Wall Street, across from the New York Stock Exchange, on September 16, 1920. At 12:01 p.m., a bomb left in a horse-drawn wagon and packed with pieces of metal exploded, killing 30 people. The most likely suspect was Mario Buda, a member of the anarchist circle in Massachusetts that Nicola Sacco and Bartelemeo Vanzetti belonged to. Sacco and Vanzetti had been arrested for murder and robbery only five days before. Five flyers were found in a mailbox a two-minute walk from the scene, deposited prior to the 11:58 pickup. One said: “Remember we will not tolerate any longer. Free the Political Prisoners or it will be death for all of you. Anarchist fighters.” Buda fled to Italy. Visit the site and you will see evidence of the bombing in the building’s granite base.

For the following 40 years, New York experienced no significant acts of terrorism. But that changed in the mid-1960s as the city became a battleground for various groups advocating racial justice, national independence, ethnic pride, and revolution. For more than two decades, the city was the scene of jetliner hijackings, attacks on police and other arms of government, and many, many bombings, several of them resulting in death and serious injury.

Some New Yorkers today are inclined to romanticize the political idealism and fervor of those years. Largely omitted from that idealized narrative is any consideration of the widespread violence perpetrated by radical groups, often acting in the name of racial or ethnic justice. To protest the treatment of Jews in the Soviet Union, young American Jews planted bombs in the offices of companies doing business with USSR; a young woman was killed by one such blast. Croatians hijacked airliners, took over the Yugoslav consulate at gunpoint, and planted a bomb in LaGuardia Airport that killed 11 and wounded 75. Members of the Weather Underground blew themselves up in a Greenwich Village townhouse while preparing bombs to plant at a dance at Fort Dix. The Black Liberation Army robbed banks and assassinated police officers on the streets.

Perhaps the most dangerous, and secretive, group was the F.A.L.N. Seeking independence for Puerto Rico, they planted bombs across the city in a campaign lasting years. Between 1974 and 1983, they were responsible for an estimated 114 bombings across the nation. Their most notorious act was the lunch hour bombing of Fraunces Tavern in lower Manhattan in January 1975, killing four and injuring 53. The bomb maker, Willie Morales, was later badly maimed by one of his own devices. He escaped from jail and is now living in Cuba.

On the right, Anti-Castro Cubans carried on their own terror campaign, targeting the consulates of governments that recognized Castro’s government, companies doing business with Cuba, and individuals seeking to normalize relations. They bombed a Soviet freighter in the harbor, Lincoln Center, Grove Press, and union halls, and they assassinated opponents. Today all memory of their actions has seemingly faded.

Despite the hundreds, literally hundreds of bombings in the city during these years, and despite the targeting of police, especially by the Black Panthers and the Black Liberation Army, law enforcement strove to identify the specific individuals involved and did not demonize a wider population. The courts demonstrated serious concern for the rights of the accused and were always alert to the possibility of police entrapment. In many cases, juries were reluctant to convict.

One of the lasting legacies of this era is the 1985 consent decree known as the Handschu Agreement. In 1971, Barbara Hansdchu and fifteen other plaintiffs, Abbie Hoffman among them, sued the police department over its practice of infiltrating and monitoring political and religious groups. Handschu prohibits the department from investigating any political or religious group unless there is specific information that a crime has been committed or is about to be committed. The NYPD petitioned to modify Handschu after the 9/11 attack to foster investigation of terrorists, and in April 2003, the United States District Court approved the modified guidelines.

Looking back from a post-9/11 perspective, the earlier episodes of terror and the response of law enforcement, the courts, and the general public, belong to another world. Today, an individual of questionable mental stability mumbling a vague threat to an undercover operative is sentenced to decades in prison. Then, individuals caught with dynamite and blasting caps received a suspended sentence, if they were even convicted. For many New Yorkers, it seemed, the bombings were just another indication of urban decay, rising criminality, and social instability.

New York enjoyed only a brief respite from Sixties-era terror before the specter of a new, seemingly open-ended age of terror announced itself. The first attack on the World Trade Center in 1993 seemed to come out of nowhere, but in fact there had been earlier acts of Islamic terror in the city. In 1989, the Ayatollah Khomeini, the Supreme Leader of Iran, issued a fatwa against Salman Rushdie for publishing his novel The Satanic Verses. After that the major bookstore chains removed the volume from their shelves, but not an independent shop in the Bronx. The Riverdale Press ran an editorial against censorship stemming from fear titled “The Tyrant and His Chains.” Soon after the paper’s office was firebombed, and a caller claimed it was in response to the fatwa. Local newspapers across the country then reprinted the editorial, and Senator Daniel Patrick Moynihan entered it into the Congressional Record.

In April 1990 a pipe bomb exploded in Uncle Charlie’s, a gay bar in the Village. Initially the police did not believe it was a hate crime (resulting in angry demonstrations by gay activists), but suspicion later fell on a certain El Sayyid Nosair, an Egyptian immigrant. Seven months later Nosair assassinated Meir Kahane, founder of the Jewish Defense League, and from his prison cell he participated in the World Trade Center bombing conspiracy. Osama bin Laden contributed to Nosair’s defense fund. The clues to that terror cell were there, but law enforcement did not put them together.

The attacks on the World Trade Center in 1993 and 2001 were entirely different from the domestic terrorism of the 1970s. In the 1970s, many Americans were sympathetic to the causes and grievances of the radicals, even if they rejected their terrorist methods. Today, few Americans support the cause of militant Islam or the nations who back them. Also different is the response of the police. Since 9/11, New Yorkers have been subject to more intrusive surveillance, and the police have shown less tolerance for the creative energy and quirkiness that made the city so dynamic. The zero tolerance approach to civic disorder and low level crime has made more New Yorkers subject to aggressive policing.

This is in sharp contrast to the previous age of urban terrorism. Police then tried to target the radicals without limiting the traditional freedoms of the city. Then too, the legal system was wary of police entrapment, the involvement of agent provocateurs, and the infringement of individual rights. Today, juries have readily convicted Islamic terrorists of conspiracy and judges have rendered long sentences. On the one hand, the criminal justice system has dealt sternly with the plots, but on the other, the public is subject to police controls far more extensive than even the most aggressive tactics of that earlier war on terror.

Still, the fact remains that New York City will be an inviting target for terror. In the past, terrorists clearly identified their cause (as muddy their thinking may have been), and their motives were understood from their own statements. The FALN demanded independence for Puerto Rico; the Weathermen sought a Marxist revolution. Why do we persist in seeking the motives of bomb making terrorists or assassins today who announce allegiance to strains of radical Islam? It benefits no one to deny the nature of our attackers by labeling their motivation as “violent extremism” as President Obama does, or the scandalous statement of Mayor de Blasio calling the Chelsea bombing an “intentional act.”

Jeffrey A. Kroessler is an urban historian and librarian at John Jay College of Criminal Justice.