(CNN) — Brenda Partridge-Brown knew for years that her mother served overseas during World War II. But she didn’t know the whole story.

Willie Belle Irvin-Partridge had regaled her six children in suburban Atlanta with stories of her time in the Women’s Army Corps, stationed in Europe.

She shared memories of the friendships she formed during the war, and her love of the lush English countryside and its charming churches. A black and white photo of her — then Willie Belle Irvin — wearing a dark khaki uniform and a military beret sat on the mantel of every home their family lived in.

But Irvin-Partridge left out a key detail: She had been a member of the historic 6888th Central Postal Directory Battalion — the only all-female, predominantly Black unit to serve in Europe during World War II. The battalion didn’t see combat, but they played a crucial role in boosting US troops’ spirits during the war’s final months.

Irvin-Partridge died of kidney cancer in 1990 at age 66, taking her secret to the grave. For years Partridge-Brown wondered how her mother, called “Madea” by her kids, ended up in the military at a time when it was segregated by both race and gender.

She had so many questions. What role did her mom play in the Army? What unit was she in? Then in 2016 Brown learned about the pioneering 6888th, nicknamed Six Triple Eight, and things began to fall into place.

“I was just fascinated…,” Partridge-Brown said. “And I’m thinking to myself, she’s got to be a part of this group of women.”

She began Googling the battalion and zoomed in on historical photos, pausing to study each of the faces.

One of the images showed a group of women soldiers standing for an inspection in England in 1945. And there, at the edge of the frame, was her mother in the second row — staring straight ahead with a stoic expression on her face.

Partridge-Brown screamed.

“My brother ran into my room and asked what’s wrong. And I said, ‘I need you to look at the computer and tell me what you see.’ I didn’t tell him anything about what I saw,” she said. “He pointed and said, ‘That’s Madea.’ My tears fell. I was unable to speak for a while.”

Members of the 6888th Battalion march in a parade in Rouen, France. Credit: Pfc. Stedman / U.S. Army/National Archives

The unit’s work remained largely unknown for years

More than 6,000 African American women served in the Army during World War II — 855 of them in the 6888th Battalion, said Col. Edna W. Cummings, a retired Army officer.

Only six of the battalion’s members are known to be alive.

The battalion’s story remained largely unknown for many decades. Only in recent years has its contributions to the war effort been widely recognized.

President Joe Biden awarded the battalion’s women the Congressional Gold Medal last year after Congress passed a bipartisan bill honoring them. And Tyler Perry will write and direct “Six Triple Eight,” a Netflix film about the women’s heroics starring Kerry Washington, Susan Sarandon and Oprah Winfrey.

Congress established the 6888 Battalion under the Women’s Army Corps in July 1943 after civil rights activists demanded that Black women also get opportunities to serve overseas.

Its members spent roughly four months training in the US before they sailed to Europe in early 1945. Their journey was not without danger — they dodged German U-boats in the North Atlantic and survived a German rocket explosion as they disembarked from their ship in England.

Once there, their mission was to help sort and distribute an enormous backlog of mail addressed to the 7 million American soldiers and government workers stationed in Europe.

Without the luxury of the internet or cellphones, letters were the main form of communication for those serving in the war. US service members, eager for word from home, were frustrated by the slow pace of mail delivery.

But daunting conditions made the women’s task anything but simple. When they arrived in Birmingham, England, the mail and packages were piled up to the ceiling in frigid warehouses with darkened windows to hide them from German bombing raids.

“It was hard, blackout conditions. We had poor lighting, poor heating. We couldn’t let the sunlight in because they were still fighting and bombing in that area,” Lena King, a former corporal and one of the unit’s last six surviving members, told CNN.

The women of the 6888th were given six months to sort out the mail. They did it in three months — working in shifts around the clock and clearing 65,000 pieces of mail per day. Their motto was “No mail, low morale.”

“Madea told me of how they had to switch jobs, depending on the shift,” Partridge-Brown said. “Sometime they even had guard duty, even though they were not allowed to carry guns.”

When the backlog in Birmingham was cleared, the 6888 Battalion sailed to France to clear another mountain of mail in Rouen.

In total, they sorted some 17 million letters and packages in a matter of months.

The women eat at a WAC mess hall in England in early 1945. Credit: Pfc. George Holt / U.S. Army/National Archives

The women faced racism from their fellow service members

Partridge-Brown, 65, says her mother’s wartime service in Europe also shaped her own life.

“My mom, sometimes, she’d be whooping you a bit too much and you’d say, ‘Calm down, the war is over. The war ended!'” she said with a chuckle.

Her mother told stories about how wine was served with every meal in France, and how she spent some weekends exploring the country’s massive cathedrals and beautiful works of art.

She also told her children about the treatment she and her fellow soldiers received overseas — a far cry from the racism they often experienced at home.

“They were treated better overseas,” Partridge-Brown said. “Much better.”

In Europe, the Black women were liberated from the Jim Crow laws that limited which establishments they could visit in parts of the US. They went out freely to restaurants and nightclubs.

“People of Birmingham, England, treated us as heroes,” King told CNN.

That was not always so true of US servicemen, she said.

King, who recently turned 100, recalled a dance at which a White American soldier asked her, “What are you doing here?” and called her the n-word.

“That was very devastating and very painful,” she said, “to see that the same countryman that you’re fighting the same war for was the one who disrespected me the most.”

After their job in France was done, the 6888th Battalion returned home without the fanfare accorded other service members.

“Our dismissal was quiet and unpronounced. We simply came home,” King said.

For decades, few publicly acknowledged the women’s role in the war, said Indiana Hunt-Martin, who was a private first class in the battalion.

“There was nobody that mentioned it. Nobody even said nothing about it, for about 70 years,” Hunt-Martin told CNN before her death in 2020 at age 98. “That’s when we started understanding what a good job we did.”

Partridge-Brown believes that may be one reason why have her mother didn’t mention her specific unit — she didn’t recognize how efficient they’d been amid the chaos of war.

Photos of Willie Belle Irvin-Partridge are displayed on a table on February 5, 2023 at the home of her daughter in suburban Atlanta. Brown is the daughter of Willie B. Irvin Partridge and is writing a book about her mother.

Brown has spent years unraveling secrets of her mom’s military past

Willie Belle Irvin-Partridge died at her house in East Atlanta, surrounded by her children and grandchildren. She was buried at South-View Cemetery, where other Black heroes, including Congressman John Lewis and baseball legend Hank Aaron, have been laid to rest.

Partridge-Brown has spent the last few years researching the battalion that was such a big part of her mother’s life. She got her military records from the Army and reached out to her mother’s hometown of Moultrie, Georgia, for any information they have on her.

She’s also visited Fort Leavenworth, Kansas, to see her mother’s name inscribed on a monument honoring the battalion. And she recently obtained a copy of her mom’s honorable discharge certificate.

“And right across it said six triple eight,” Partridge-Brown said.

She learned her mother had joined the Women’s Army Corps to help out her parents.

“Things were so bad and they needed money,” Partridge-Brown said. “She and my uncle in the military both sent allotments home. They were able to get a nice home for them.”

Through her research, Partridge-Brown learned that her mother served as a cook in England and later helped sort mail in France. After her discharge in March 1946, she used the GI Bill to take classes at the University of Florida and became a dietician.

Inside Partridge-Brown’s red brick bungalow in the Atlanta suburb of Decatur is a corner dedicated to her mother. Its shelves are stacked with an assortment of photos, medals and newspaper headlines. On one shelf, next to an American flag, is an Oscar-like award with “World’s best grandma” written on it.

And like a bridge connecting the past to the future, the portrait of her mother in uniform that sat on the mantel of their family homes for decades is still proudly displayed.