Before she was known around the world for living with mountain gorillas, Dian Fossey struggled to bring attention to their dwindling numbers.

Certain that gorillas were on the verge of extinction, she adopted a brash approach to communication and conservation that ruffled many—and likely contributed to her still-unsolved murder in 1985. But this fierce dedication also helped revive the beleaguered primates. Today, thousands of tourists visit Rwanda, Uganda, and the Democratic Republic of the Congo to see them.

In 1969, the 35-year-old scientist had received three National Geographic Society grants to research the elusive gorillas, and the magazine’s editors decided to feature her findings. They quickly learned that Fossey was not afraid to offend in the gorillas’ defense.

On June 1, 1969, a letter arrived from Fossey at National Geographic headquarters in Washington, D.C., one of hundreds of pages of correspondence and observation journals that fill a shelf in the Society’s archive. The letter was addressed to W. Allan Royce, an illustrations editor who had sent her draft artwork for the article, and it was blistering.

“My initial reactions to the dummy,” she wrote, “are to applaud the stamped ‘Not for Publication’ on the slides of the two sketches and to underline the word ‘tentative’ on the first page.”

She was sickened, she told a text editor in another letter, by how the gorillas were being portrayed. “Please don’t cheapen this animal,” she wrote. The illustrations, since lost to time, may have depicted a gorilla charging Fossey, with a caption describing them as “savage.” This incident happened only once, she noted, in more than two thousand hours of gorilla observation.

“[The sketch’s] purpose was to show that, regardless of gorilla behavior, your work is not without incident and potential hazard to life and limb,” Royce reassured her.

The problems with National Geographic’s January 1970 issue—which ended up featuring Fossey on the cover—had just begun. Two months after the initial dispute about images, an editor named RL Conly took a look at Fossey’s story and unleashed his critique: “The author has written a rambling account of some rather odd adventures in the Virunga Mountains,” he wrote. “Her house catches fire. She kidnaps a native boy. The boy’s father steals her dog. She ‘holds for ransom’ another native’s cattle (to get her dog back). She dresses up in a Halloween mask to spook the natives; they’re disturbing her gorillas.”

Fossey’s scientific findings were absent from her writing, and Conly worried she’d be compared unfavorably to Jane Goodall and her popular articles about chimp research in Gombe, Tanzania. So Fossey swapped out ad-hoc adventures for research and observations, and the illustrations department at National Geographic erased the word “savage” from the mock-up pages.

By the time Fossey first set up her research station, Karisoke, in what is now Volcanoes National Park in Rwanda, decades of poaching had taken their toll. She feared that gorillas would be extinct within 30 years if nothing was done to protect them, and took it upon herself to be both conservator, spokesperson, and detective. Patrolling the park each day, she and her research team would collect hundreds of wire traps set by poachers to ensnare gorillas to sell their body parts and infants.

She was less concerned about humans. Her treatment of local Rwandans was often offensive; in her letters she sometimes calls members of her research team and park staff “my Africans.” Her journals and letters boil with anger at the badly trained, often corrupt staff. In a letter to a National Geographic researcher she wrote, “The term ‘Park Service’ is a wee bit flowery to describe the services of the 6 poorly clothed, chronic alcoholics that fearfully attempt to serve as guards in this area.” The guards sometimes didn’t receive their government wages for months. Instead, they’d take payment from poachers to enter the park, and even sell them their guns.

In 1968, just as Fossey was settling into her research camp, the chairman of the International Commission on National Parks visited the gorilla’s range and drafted a dismal report. Albert National Park—the colonial-era name for the entire range—was created in 1925 “to make the world safe for gorillas,” he wrote. But it had failed. The report describes hunting parties organized for sport, a plundered ranger station, and insufficient supplies: “Tents, spare waistbelts, puttees, shoes, rucksacks, caps, badges have run out.”

In the absence of effective guards, Fossey began investigating herself. She noticed that bullet cartridges were being removed from the scene of gorilla murders, preventing anyone from tracing the caliber of the gun. “The possibility therefore arises that the gun involved recently is a known gun ‘borrowed’ for the killings perhaps from the park guards?” she wrote.

In a 1978 conversation with the park head, Fossey was told that he didn’t have the authority to raid poachers’ camps outside the park boundaries or to shoot them inside the park. In response, she suggested he and his deputies be fired.

Her journals aren’t all frustration. Daily reports are peppered with breakthrough research. A 1971 entry titled “Mirror Incident” describes watching her favorite gorilla, a young male named Digit, look at himself in a mirror: “He began to twist his head back and forth like a teenager primping for prom,” she wrote. When, six years later, Digit was killed by poachers, he became the face of Fossey’s global campaign to save the gorillas. She founded the Digit Fund, which is now the Dian Fossey Gorilla Fund and continues her conservation work today.

By 1980 there was a 130 percent increase in tourists coming to visit the gorillas. There were four gorilla guides, working out of a new headquarters with new uniforms and radios. “For the first time ever, the PNV [Volcanoes National Park] is receiving more money than it is [has?] spent to operate the park,” a report said.

Two years later, Fossey describes a poacher being caught trying to smuggle a month old baby gorilla out of the park. For the first time, a guard shot and killed one of them. This was the kind of active protection Fossey had been advocating.

In 1986, the year after her murder, there were 280 mountain gorillas left in the range that straddles Rwanda, Uganda, and the Democratic Republic of the Congo. Today, there are 880 gorillas and their numbers are increasing. The three parks still practice an aggressive style of conservation. When Fossey was working in Rwanda it was one of the poorest countries in Africa, but the country has since become one of its most lauded economic success stories. The gorillas are being protected and, in return, Rwanda expects to bring in $444 million in tourism this year.