It's official: Uber's founder, Travis Kalanick, has resigned as CEO of the company.

Travis Kalanick stepped down Tuesday as chief executive of Uber, the ride-hailing service that he helped found in 2009 and that he built into a transportation colossus, after a shareholder revolt made it untenable for him to stay on at the company.

Mr. Kalanick's exit came under pressure after hours of drama involving Uber's investors, according to two people with knowledge of the situation, who asked to remain anonymous because the details are confidential.

The report describes how five of Uber's major investors came together to demand that Kalanick resign immediately, via a letter entitled "Moving Uber Forward." Investors wrote that the company "needed a change in leadership." After some long discussions, Kalanick acquiesced.

This is certainly a challenging time for the former company head, who lost his mother last month to a tragic boating accident (which also left his father seriously injured). Kalanick will remain on Uber's board of directors.

"I love Uber more than anything in the world and at this difficult moment in my personal life, I have accepted the investors' request to step aside so that Uber can go back to building rather than be distracted with another fight," said Kalanick in a statement.

How a single (massively viral) blog post started it all.

I've followed Uber from the beginning, viewing the company as a fascinating case study in leadership, branding, strategy and organizational culture.

So I, along with thousands of others, was horrified to read the allegations of one of Uber's former female engineers, Susan Fowler. In a blog post on her personal website, entitled "Reflecting on One Very, Very Strange Year at Uber," Fowler accused numerous members of Uber's management team of:

  • explicit sexual harassment;
  • gender discrimination;
  • intentional deception;
  • career sabotage; and
  • illegal threats of termination of employment.

Unfortunately, single allegations like this rarely make major waves against major companies.

But this time would be different.

In the four months (four months!) since Fowler published her account, the following has happened:

  • Uber's board initiated an extensive investigation, led by former Attorney General Eric Holder;
  • a number of top executives either resigned or were fired;
  • another 20 employees were fired over harassment, discrimination and inappropriate behavior;
  • a prominent member of Uber's board was forced to resign after making a comment many deemed as sexist (at a meeting addressing sexism at Uber);
  • Wan Ling Martello, head of Nestle in Asia, joined Arianna Huffington to become Uber's second female board member;
  • Uber's U.S. market share declined from 84 to 77 percent, reports the Financial Times, while chief competitor Lyft launched operations in 150 new cities and gained market share; and
  • Uber's founder and CEO, Travis Kalanick, was forced to resign.

This type of cataclysmic change would be remarkable for any organization.

But can we pause for a moment, to appreciate what initiated this amazing upheaval in the first place?

It was a single blog post, by a junior engineer.

There is no way Fowler could have possibly predicted the repercussions her blog post would have.

But there is a major lesson in her story:

It takes great courage to stand up for what you believe in, to call out what you know is wrong, despite the odds being stacked against you.

So for everyone out there who feels that it's you against the world, that the fight for what is right is almost too much to bear, and that a single voice might not be enough, I implore you to remember Susan Fowler.

Because sometimes, a single voice is loud enough.