John Kelly has been officially sworn in as the new Chief of Staff at the White House just days after the departure of Reince Priebus.
Speaking from the White House, President Donald Trump predicted that Kelly would do a "spectacular job."
Kelly, a four-star general, has a military background spanning four decades and has spent the past few months heading up the Department of Homeland Security.
He is highly respected, but will be tested by a White House in chaos.
Trump, speaking about Kelly said: "I have no doubt, what he has done in terms of homeland security is record-shattering, you look at the border, you look at the tremendous results we've had."
In 2012, Trump criticised Barack Obama for having three chiefs of staff in as many years. Trump is now on his second in six months.
Priebus's time as chief of staff was the shortest ever. And once Anthony Scaramucci was in the White House, he soon began gunning for Priebus.
He called Priebus "a f****** paranoid schizophrenic" and accused him of leaking.
Days later, as Trump and his team arrived back in Washington from a trip to Ohio, Priebus was effectively carted off on the runway as Trump waved from the steps of Air Force One.
A black SUV next to the plane took Priebus away from the presidential motorcade, marking the end off their working relationship.
As the car was driven away, Trump spoke to TV cameras and said: "John Kelly will do a fantastic job. General Kelly has been a star, done an incredible job thus far, respected by everybody, a great, great American. Reince Priebus is a good man. Thank you very much."
It has been a busy time for the White House, with Trump attempting to corral support for a repeal and replace of Obamacare, which failed.