More than a century ago, Juliette Gordon Low dared to change the name of the Girl Guides to the Girl Scouts. She outraged the Boy Scouts of America, whose chief scout executive, James E. West, accused the GSUSA of “trivializ[ing]” and “sissify[ing]’’ his group.

But now it is the Boy Scouts of America that has decided to drop the word “Boy” from the name of its flagship program, a bold move that closely follows the organization’s decision to admit girls. More than 3,000 girls have already signed up for the Cub Scouts as part of an “early adopter” program. The organization plans to allow girls ages 11 to 17 next year.

On the one hand, the decision is a long-overdue shift for a group with a history of exclusion. On the other, the move threatens to trivialize the unique historical legacy and the feisty “girls-doing-it-for-themselves” spirit of Low.

At a time when the Boy Scouts is trying to blur the distinctions between the groups, it is important to remember that an original act of gender-based segregation gave rise to the Girl Scouts movement in the first place. Long before Scouting made a place for them, girls were besotted with the idea of exploring woodlands, vying for badges and learning to tie up burglars with short lengths of twine — activities that were just as empowering as the community of sisterhood the organization also cultivated.

The Boy Scouts began in Britain, when its founding father, Robert Baden-Powell, published his best-selling “Scouting For Boys” in 1908. He founded the organization out of concern that too many English boys were becoming slothful, soft-bodied hooligans, morally and physically atrophied in an era of increasing urbanization.

The popular movement for youth reform, combined with the unstoppable enthusiasm and charisma of Baden-Powell himself, helped turn Scouting into a worldwide phenomenon, with an emphasis on competitions, camp-outs, patrols and woodcraft skills. But the 6,000 girls who quickly tried to join the Boy Scouts were turned away.

Some girls left their initials on sign-up sheets in the hopes that they would be mistaken for boys. A few marched behind the boys while wearing homemade uniforms and ersatz badges. Unmoved, Baden-Powell left it to his sister, Agnes, to create a feminized British spinoff called the Girl Guides. Low helped expand the group before returning to the United States and starting her own chapter.

With a clear and confident vision of empowerment for girls, Low launched her chapter of the Girl Guides in Savannah, Ga., in 1912, two years after the inception of the Boy Scouts of America. As far as she was concerned, girls needed to learn camaraderie, lifelong leadership skills, survival techniques and the value of competition in their own separate sphere, far from the watchful and judgmental gaze of boys and men.

The Girl Guides appealed to worried parents who wanted their girls to grow up virtuous and strong, trained in the domestic arts and with a strong sense of morality, patriotism and discipline. But Low also emphasized skills that bucked gender rules, from fort-building to signaling to animal tracking — traditionally masculine activities.

Soon after Low established the Girl Guides in the United States, her young charges persuaded her to change the organization’s name to the Girl Scouts, in part because they thought that “Scouts” conveyed fun and adventure, while “Guides’’ made them seem like passive help meets of the daring and resourceful Boy Scouts.

Low was careful not to threaten gender rules in any obvious way. Indeed, she steeped the girls in home economics, knowing that most of them would grow up to be housewives. The organization, for example, offered a “Laundress Badge.’’ But Stacy Cordery, author of the biography “Juliette Gordon Low: The Remarkable Founder of the Girl Scouts,” argues that Low also wanted the girls to have “something extra,” a contingency plan to help them survive in case these marital unions took a bad turn.

Low learned, from miserable firsthand experience, that a woman could follow the rules set down by men and still lose. Low’s husband, a feckless British playboy and gambler named William Mackay Low, felt that he had the right to “treat her as a dog,’’ in the words of Juliette Low’s sister. Her husband openly cheated on her, then dropped dead before she could finalize divorce proceedings against him.

Furious, childless, middle-aged and jobless at a time when motherhood and housewifery determined a woman’s worth, Low was bereft and bitter. But the Girl Scouts gave her a purpose and mission. Meanwhile, the military buildup toward World War I provided a good excuse for the Girl Scouts to learn about firearms, signaling and reconnaissance, map-reading and tree-fort building. They also received career guidance counseling: An early handbook let the girls know that they could be stockbrokers or aviators if they so desired.

The GSUSA has grown into the most important girls’ movement in U.S. history, in part because it offered intensive leadership training that many girls could not get anywhere else, along with an emphasis on volunteerism, sisterhood and civic duty. Perhaps unsurprisingly, its 50 million alumnae include many influential women, among them Hillary Clinton, Chelsea Clinton, Sandra Day O’Connor, Condoleezza Rice, Taylor Swift, Venus Williams and Barbara Walters.

Central to its success has been its history of inclusion, part of the Girl Scouts’ recruitment and expansion strategy over the years. The GSUSA never took an official position on lesbian Girl Scouts until the 1980s, when the organization stated that it “does not discriminate or intrude on personal matters.” By contrast, the BSA banned openly gay scouts until 2013, and gay leaders until 2015.

But now, BSA seems to be copying Low’s strong emphasis on the value of single-gender scouting and education. Among other things, the organization will have all-girl Cub Scout dens. In the process, the two organizations are starting to blur in public perception. Online forums are already full of comments by confused parents: Which group is better for my girl?

The same group that is now opening its doors so enthusiastically to female members once accused Low of turning girls into tomboys and invading the territory of men. This may be a triumph for the concept of inclusion, but it may well undermine the Girl Scouts by turning the Boy Scouts into a direct competitor, siphoning off its members.