For Ms. Sandberg, moving to Facebook, a company run by an awkward 23-year-old college dropout, wasn’t as counter-intuitive as it might seem. She was a vice president at Google, but she had hit a cap: there were multiple vice presidents at her level, all of whom were battling for promotions. Eric Schmidt, the managing director at the time, wasn’t looking for number 2. Men who weren’t as good as her would be recognized and given higher titles, former Google colleagues claimed.

“Although she ran a bigger, more profitable, and faster growing company than her colleagues, she wasn’t made president, but they did,” recalls Kim Scott, a director of advertising sales. Mrs. Sandberg was looking for something new. She said yes to facebook.

Mr. Zuckerberg brought in Ms. Sandberg to deal with growing unease about the Washington company. There she professionalized the jumbled office that a recent college graduate had opened whose main task was to help lawmakers set up their Facebook accounts. She represented Facebook as a member of President Barack Obama’s Council on Jobs and Competitiveness, along with other business executives and union leaders. After a council meeting, she took Obama with Air Force One to Facebook headquarters, where the president was holding a public town hall to discuss the economy. But soon there were cracks in the facade.

In October 2010, she met with FTC Chairman Jonathan Leibowitz to break a privacy investigation. In his office, a relaxed and confident Ms. Sandberg began the meeting by claiming that Facebook had given users more control over their data than any other internet company and that the company regretted most for not clearly communicating how its privacy policy works.

The FTC officials immediately challenged them, according to those attending the meeting. Mr. Leibowitz noted that he had personally seen his middle school daughter struggle with privacy settings on Facebook, which automatically made it easier for strangers to find users like her. “I see it at home,” he said.

“That’s so great,” replied Ms. Sandberg. She went on to describe the social network as “empowering” young users. Mr. Leibowitz hadn’t taken it as good news – and told her that the FTC was very concerned about privacy.

Ms. Lever, the Facebook spokeswoman, described the meeting as “content” and explained the company’s data protection guidelines in detail. She added that the characterization of the tension in the room “misrepresents what actually happened”.