Defense Secretary James Mattis put out his first all-hands message to everyone in the Department of Defense on Friday, and it tells you everything you need to know about how he intends to lead.

Mattis, a retired Marine general revered by his troops, probably made a good first impression among the roughly three million men and women who make up the active duty, reserve, and civilian force. That's due to the notable language he used in his first sentence (emphasis added):

"It's good to be back and I'm grateful to serve alongside you as Secretary of Defense."

As many who served under him can attest, Mattis has always been a humble warrior who led Marines from the front — not from an air conditioned bunker. And the language that he used — serve alongside you, as opposed to lead, or manage you — shows that Mattis will likely bring his beloved leadership style of the Marines with him into the civilian post.

"He's a leader by example," retired Sgt. Maj. of the Marine Corps Carlton Kent told Business Insider in December. "He's not the type that's 'do as I say, not as I do.' He's out there doing it."

Secretary of Defense James Mattis and U.S. Marine Corps Gen. Joseph Dunford, Chairman of the Joint Chiefs of Staff, arrive at the Pentagon in Washington, D.C., Jan. 21, 2017. | DOD photo by Air Force Tech. Sgt. Brigitte N. Brantley

Mattis kept his message short and sweet, praising the people who make up the DoD, calling America a "beacon of hope," and pledging that he would do his best as Defense Secretary.

Here's the full letter: