Here's the internal memo Rupert Murdoch just sent Fox News staff after the first day of the post-Bill O'Reilly era

Rupert Murdoch on Tuesday congratulated Fox News staff in an internal memo after the first day of the network's new lineup unveiled after star host Bill O'Reilly's departure.

"Last night's ratings are in and I couldn't be more proud to announce that, not only did FOX News beat all other cable news competition with our new primetime debut, but we also increased our ratings 31% in total viewers and 54% in the demo compared to last year," the executive chair of 21st Century Fox wrote in a memo obtained by Business Insider.

"This was a stellar performance that couldn't have happened without the amazing effort and dedication from everyone on the team over the last week," he said.

Murdoch continued: "I know the last few weeks have been tough for everyone here, but our passion for news and commitment to our viewers continue to lead us through. Congratulations and thank you for all your hard work."

Fox's new lineup on Monday indeed drew a notably sizable viewership despite the absence of O'Reilly, long the ratings king of cable news.

On Monday, Tucker Carlson, who took over O'Reilly's 8 p.m. time slot, drew just under 3.2 million viewers, far more than the entire 8 p.m. viewership of CNN and MSNBC combined. Though he did not match O'Reilly's viewership, Carlson delivered almost exactly the same number of viewers in advertiser's coveted 25-54 age demographic as O'Reilly did his final show.

"The Five," which now occupies Carlson's former 9 p.m. time slot, also debuted to strong ratings, besting MSNBC's Rachel Maddow, who notably overtook Carlson among viewers 25-54 years old in March.

It remains to be seen whether the network can sustain the audience that O'Reilly drew. Last week's fill-in hosts, Dana Perino and Eric Bolling, failed to match O'Reilly's numbers.

The network has faced increased negative scrutiny and potential legal trouble following the release of New York Times story earlier this month detailing a long history of sexual harassment allegations against O'Reilly, the network's decades-long marquee star.