The city of Birmingham, Alabama, was founded in 1871 and rapidly became the state’s most important industrial and commercial center. As late as the 1960s, however, it was also one of America’s most racially discriminatory and segregated cities.

Alabama Governor George Wallace was a leading foe of desegregation, and Birmingham had one of the strongest and most violent chapters of the Ku Klux Klan (KKK). The city’s police commissioner, Eugene “Bull” Connor, was notorious for his willingness to use brutality in combating radical demonstrators, union members and any Black citizens.

Precisely because of its reputation as a stronghold for white supremacy, civil rights activists made Birmingham a major focus of their efforts to desegregate the Deep South.

In the spring of 1963, Martin Luther King Jr. had been arrested there while leading supporters of his Southern Christian Leadership Conference (SCLC) in a nonviolent campaign of demonstrations against segregation. While in jail, King wrote a letter to local white ministers justifying his decision not to call off the demonstrations in the face of continued bloodshed at the hands of local law enforcement officials.

His famous “Letter from a Birmingham Jail” was published in the national press, along with shocking images of police brutality against protesters in Birmingham that helped build widespread support for the civil rights cause.

Many of the civil rights protest marches that took place in Birmingham during the 1960s began at the steps of the 16th Street Baptist Church, which had long been a significant religious center for the city’s Black population and a routine meeting place for civil rights organizers like King.

KKK members had routinely called in bomb threats intended to disrupt civil rights meetings as well as services at the church.

At 10:22 a.m. on the morning of September 15, 1963, some 200 church members were in the building—many attending Sunday school classes before the start of the 11 am service—when the bomb detonated on the church’s east side, spraying mortar and bricks from the front of the church and caving in its interior walls.

Most parishioners were able to evacuate the building as it filled with smoke, but the bodies of four young girls (14-year-old Addie Mae Collins, Cynthia Wesley and Carole Robertson and 11-year-old Denise McNair) were found beneath the rubble in a basement restroom.

Ten-year-old Sarah Collins, who was also in the restroom at the time of the explosion, lost her right eye, and more than 20 other people were injured in the blast.

The bombing of the 16th Street Baptist Church on September 15 was the third bombing in 11 days, after a federal court order had come down mandating the integration of Alabama’s school system.

In the aftermath of the bombing, thousands of angry Black protesters gathered at the scene of the bombing. When Governor Wallace sent police and state troopers to break the protests up, violence broke out across the city; a number of protesters were arrested, and two young African American men were killed (one by police) before the National Guard was called in to restore order.

King later spoke before 8,000 people at the funeral for three of the girls (the family of the fourth girl held a smaller private service), fueling the public outrage now mounting across the country.

Though Birmingham’s white supremacists (and even certain individuals) were immediately suspected in the bombing, repeated calls for the perpetrators to be brought to justice went unanswered for more than a decade. It was later revealed that the FBI had information concerning the identity of the bombers by 1965 and did nothing. (J. Edgar Hoover, then-head of the FBI, disapproved of the civil rights movement; he died in 1972.)

In 1977, Alabama Attorney General Bob Baxley reopened the investigation and Klan leader Robert E. Chambliss was brought to trial for the bombings and convicted of murder. Continuing to maintain his innocence, Chambliss died in prison in 1985.

The case was again reopened in 1980, 1988 and 1997, when two other former Klan members, Thomas Blanton and Bobby Frank Cherry, were finally brought to trial; Blanton was convicted in 2001 and Cherry in 2002. A fourth suspect, Herman Frank Cash, died in 1994 before he could be brought to trial.

Even though the legal system was slow to provide justice, the effect of the bombing of the 16th Street Baptist Church was immediate and significant.

Outrage over the death of the four young girls helped build increased support behind the continuing struggle to end segregation—support that would help lead to the passage of both the Civil Rights Act of 1964 and the Voting Rights Act of 1965. In that important sense, the bombing’s impact was exactly the opposite of what its perpetrators had intended.