Recent church fires in the aftermath of the mass shooting at the Emanuel AME Church in Charleston, South Carolina, have invoked painful memories of the long, terrible history of attacks on African-American religious institutions.

Officials haven't released evidence that suggests the recent church fires were hate crimes, and most aren't being investigated as arson, according to the Los Angeles Time's Matt Pearce. The handful of reported church fires also aren't out of the norm — there were an average of 31 church fires a week in the US between 2007 and 2011, according to National Fire Protection Association data uncovered by Pearce.

But while these fires may not be linked to hate crimes, there is a long history of white supremacist attacks on black churches — and these attacks often had the explicit goal of terrorizing black communities to impose racist laws and policies on African Americans.

Black churches were sanctuaries for black Americans — and threats to white power

Historically, black churches are not just houses of worship — they have also acted as sanctuaries from racism and organizational hubs for civil rights rallies. Many of the civil rights leaders of the past few decades have even come from churches, including Rev. Martin Luther King Jr.

White supremacists throughout American history often saw these churches as threats, making them prime targets for those who wanted to terrorize and maintain control of black communities and enforce slavery and segregation.

"If you want to get rid of a number of black people, you go to where they congregate — and that was churches," Gerald Horne, a civil rights historian at the University of Houston, said.

As the Washington Post's Sarah Kaplan explained, Charleston's Emanuel AME Church was started in 1816 by Morris Brown, a founding pastor of the African Methodist Episcopal Church, who was fed up with the racism he encountered in other churches in the area.

"If you want to get rid of a number of black people, you go to where they congregate"

The church hosted some of the prominent black activists of the time. Denmark Vesey, a founding member of the church, at one point attempted to lead one of the nation's most famous failed slave uprisings, which would have involved more than 9,000 black slaves. But the revolt was foiled when several slaves turned Vesey in, leading to his capture, a trial, and hanging.

White leaders blamed the attack on the Emanuel AME Church, saying it helped foster the attacks. They instituted harsh laws against black churches, including a ban on all-black services. The congregation was then dispersed, and the church was burned. (The congregation would continue to meet in secret.)

In many ways, the Emanuel AME Church's experience represented the history of black churches in general: it was used to evade the systemic racism of the era, and it was attacked by white leaders who wanted to keep their racist policies in place. "That is a microcosm of how and why churches have become targeted," Horne said.

The attacks of black churches were only a small part of how white supremacists attacked and terrorized black people — often using lynchings and other sporadic acts of violence to, for example, prevent black people from voting or protesting racist laws like slavery and segregation. These attacks became so common after the Civil War that they led Congress to pass what was essentially the nation's first anti-terrorism law in 1871, the Ku Klux Act.

But the attacks on churches — and black people in general — continued through the 19th and 20th centuries, including a wave of firebombings of black churches in the South in the 1990s and a burning of a black church in Massachusetts the day President Barack Obama was inaugurated, as the Atlantic's Conor Friedersdorf reported. But perhaps the most well-known attack was in Birmingham, where a bombing of the 16th Street Baptist Church left four girls dead.

Birmingham was at the center of attacks on churches

Civil rights groups during the early 1960s actively targeted Birmingham for protests, knowing that the city — and the state of Alabama as a whole — was a hub for white supremacy groups and supporters of segregation. The backlash was fierce: Ku Klux Klan members routinely called in bomb threats — and others exploded homemade bombs — to disrupt civil rights meetings and church services, earning Birmingham the nickname "Bombingham." The anger eventually led to one of the most well-known terrorist attacks of the civil rights movement.

On September 15, 1963, a bomb detonated at the predominantly black 16th Street Baptist Church in Birmingham. About 200 people were in the building, according to History.com, many attending Sunday school. Four black girls died, and at least 20 others were injured.

News wire service UPI described the aftermath in 1963:

Parts of brightly painted children's furniture were strewn about in one Sunday School room, and blood stained the floors. Chunks of concrete the size of footballs littered the basement. The bomb apparently went off in an unoccupied basement room and blew down the wall, sending stone and debris flying like shrapnel into a room where children were assembling for closing prayers following Sunday School. Bibles and song books lay shredded and scattered through the church. In the main sanctuary upstairs, which holds about 500 persons, the pulpit and Bible were covered with pieces of stained glass.

It was the fourth bombing in Birmingham in four weeks and the 21st in eight years, UPI reported at the time. Up to that point, none of the bombings had been resolved in court.

It took decades to deliver justice in Birmingham

As is emblematic with these types of attacks on black communities, it took very long for victims to get justice. For black communities, this is yet another way they've been oppressed: not only are their churches targets of attacks, but law enforcement acts much more slowly to solve the crimes.

The investigation into the Birmingham church bombing, the most high-profile of the cases, didn't lead to justice for decades. Robert Chambliss was convicted to life in prison in 1977, Bobby Cherry and Thomas Blanton were indicted in 2000 and later convicted to life in prison, and a fourth suspect, Herman Cash, died in 1994 before he could face trial.

For some, the feeling of neglect remains. When Congress in 2013 commemorated the victims of the Birmingham church bombing, some of the survivors and relatives told the Associated Press's Jay Reeves they weren't interested. Sarah Rudolph said she wanted compensation for the injuries she suffered, including a lost eye, and for the death of her sister, who was one of the girls killed.

"We haven't received anything, and I lost an eye," Rudolph told the AP. "It's a smoke screen to shut us up and make us go away so we'll never be heard from again."