In 1909, a group of young women marched on a rally in Crystal Palace, London, calling to be part of the newly formed Scout movement. These girls were bold; their actions transformative.
Anything boys could do, girls could do too - and these girls believed they could do anything.
Today, girls globally still want to push boundaries. They want to make their voices heard, contribute to society and lead lives that can transform their communities. They don't need people, experts or NGOs to tell them what needs to be done. In fact, girls are the experts on their own needs and their lived realities - they just need to be given the opportunity, skills and support to make their voices heard.
On International Day of the Girl, now more than ever is the time to shout about the importance and the potential of girls. But, really, it shouldn't just be confined to one day. Girls' rights and girls' voices are important every day of the year.
Our organisation, the World Association of Girl Guides and Girl Scouts, is empowering girls around the world to tackle the issues that matter to them. Our non-formal education approach - which relies on experiential, hands-on learning - helps to make complex topics accessible and fun for young people. Our values-based approach also equips girls and young women with the desire, the confidence and the skills to translate what they've learned into practical action in their communities.
Taking the lead
There are 10 million Girl Guides and Girl Scouts in 146 countries worldwide. From responding to natural disasters and challenging gender-based violence to educating girls on health issues, these young women are taking the lead and working to improve their communities for the better.
I've met many of these girls and they've shared heartening - and inspiring - stories about the projects they've set up.
When hundreds of thousands migrants and refugees entered Europe by sea, with over 100,000 migrants or refugees arriving in Greece and Italy this year, Greek Girl Guide leader Olympia was determined not to be a bystander.
Olympia and her Girl Guides troop decided to step forward and respond to the crisis.
"I don't want Greek society to see refugees as a threat," she explained. "I want them to understand the hardship that refugees, especially girls, endure. That's why groups of Girl Guides, age 14 to 17, are going to the islands where refugees are living and distributing food and aid. We want to make them feel as safe and comfortable as possible."
In Sri Lanka, Girl Guides are campaigning against gender-based violence, delivering educational workshops across the country and raising awareness in bus stations, on the streets and in the halls of Parliament.
Chamathya, 23, has been a Girl Guide since she was eight. She's experienced violence first-hand.
"Girls face harassment on a daily basis while commuting on public transport," she said. "It's at risk of becoming normalised in my country. Whether verbal or physical, sexual harassment is a violation of women's rights."
Now, this inspiring young woman is educating others, changing minds and organising young people to stop the violence in her country.
"I want to change this culture of silence. I want girls and women to realise they are allowed to have a voice, share their experiences and speak up for their rights," said Chamathya.
Girl Guide leader, Lucy, lives in Malawi. Her aim is to educate girls about health issues. With 34% of adolescent girls in Malawi falling pregnant before the age of 18, it's an important issue that needs to be tackled.
"Talking about sex and menstruation can be tough for some girls. They can find it embarrassing, or because of the taboo nature of the subject, it may be something they know nothing about," said Lucy.
"Our projects aim to ensure adolescent girls are informed about and empowered to access health services that address sex education, HIV/AIDS and gender-based violence for girls who are both in and out of school."
A global movement
These are just a few examples from across our global movement and it's incredible to see Girl Guides and Girl Scouts taking action on the issues that matter to them.
However, if we want to see girls really flourish it means we have to do our part too. Just over one year ago, in September 2015, world leaders came together to adopt the Sustainable Development Goals, an ambitious agenda to tackle poverty, climate change, and all forms of inequality by 2030. If we are to achieve these ambitious goals, we must recognise the power and potential of girls. The Global Goals will only ever be achieved if governments, businesses, communities and civil society invest in girls and women and give them the tools they need to lead and thrive.
What's clear to me is girls have the enthusiasm, passion and desire to change their communities for the better. It's about time the world sat up and not only took notice, but gave girls the belief, support and tools to thrive. What they could achieve would be truly limitless.
To mark International Day of the Girl 2016, the World Association of Girl Guides and Girl Scouts has launched #TeamGirl, a campaign that highlights girls and young women tackling real issues and making a difference in their communities today and in the future. To find out more and join the movement, visit www.wagggs.org/teamgirl