 -- President-elect Donald Trump announced Thursday night that he will "appoint" retired Marine Gen. James "Mad Dog" Mattis to be his secretary of defense. The two met in Bedminster, New Jersey, in November for an hour, after which Trump called Mattis the “real deal.”

Under the Appointments Clause of the U.S. Constitution, certain federal positions appointed by the president -- including secretary of defense -– require confirmation of the U.S. Senate.

Mattis most recently served as the head of U.S. Central Command. A lifelong bachelor, he is known as the “warrior monk” for his knowledge of ancient and military history.

The four-star general is revered by many for his leadership and also known for his blunt words.

Here are seven quotes -- or “Mattisisms” -- from the retired general on war, leadership and the U.S. Marines:

“Bloom where you are planted.”

A fellow Marine Corps officer says this was Mattis’ simple philosophy. If he didn’t like an assignment he was given, his attitude was to always do the best that he could.

"Be polite, be professional, but have a plan to kill everybody you meet."

Mattis shared this quote with his Marines as a rule to live by in Iraq, Thomas E. Ricks writes in “Fiasco: The American Military Adventure in Iraq.”

“Marines don’t know how to spell the word defeat.”

Mattis joined the Marine Corps when he was just 19. He's considered one of the more intense military intellectuals and owned a huge personal library, according to Ricks' book.

“You are part of the world’s most feared and trusted force. Engage your brain before you engage your weapon.”

This quote is from a letter Mattis wrote to his Marines the night before the March 2003 Iraq invasion.

"It’s all the more important today that we hold to our precious legacy of ferocious, ethical combat performance."

Mattis delivered these remarks during his speech at the Marine Corps University Foundation’s 2014 Semper Fidelis Award Dinner on Feb. 22, 2014.

“Marines who can do the necessary ‘rough work,’ but without becoming evil by doing so, despite an enemy who has opened apocalyptically the aperture for who they target, to include even women and children," Mattis said. "It’s all the more important today that we hold to our precious legacy of ferocious, ethical combat performance. For in a world awash in change, Americans need to have confidence in the everlasting character of our Marines.”

"Actually it's quite fun to fight them, you know. It's a hell of a hoot. It's fun to shoot some people.”

According to CNN, Mattis said he “should have chosen his words more carefully” after receiving counsel from the Commandant of the Marine Corps, Gen. Michael Hagee, for comments he made during a 2005 panel discussion about fighting the Taliban.

"Actually it's quite fun to fight them, you know. It's a hell of a hoot. It's fun to shoot some people,” Mattis said at the time to the Armed Forces Communications and Electronics Association. “I'll be right up there with you. I like brawling.”

Mattis continued, “You go into Afghanistan, you got guys who slap women around for five years because they didn't wear a veil. You know, guys like that ain't got no manhood left anyway. So it's a hell of a lot of fun to shoot them."

Gen. Hagee defended Mattis’ comments in a statement provided to CNN: "While I understand that some people may take issue with the comments made by him, I also know he intended to reflect the unfortunate and harsh realities of war. Lt. Gen. Mattis often speaks with a great deal of candor."

“But there was another word that I learned to prioritize as I evaluated units, and that word was affection."

In a Marines video posted on Oct. 13, 2016, Mattis revealed his “leadership lessons” from his 41-year long career in the corps.

"It’s not popularity -- with all the favoritism that comes with trying to be a popular person as a leader. That’s a road to failure," Mattis said. "But affection that you create in a unit, an affection so strong that the troops will stick by one another and carry out the mission even in peril."