Departing Defense Secretary James Mattis said in a farewell message to Department of Defense employees on Monday that the department is 'proven to be at its best when the times are most difficult' and urged employees to 'keep the faith in our country.'
'Our Department is proven to be at its best when the times are most difficult,' Mattis wrote. 'So keep the faith in our country and hold fast, alongside our allies, aligned against our foes.'
Mattis also expressed confidence in the department's leadership as his deputy defense secretary, Patrick Shanahan, prepares to take over as acting secretary.
'Our Department's leadership, civilian and military, remains in the best possible hands. I am confident that each of you remains undistracted from our sworn mission to support and defend the Constitution while protecting our way of life,' his statement read.
Mattis concluded, 'It has been my high honor to serve at your side. May God hold you safe in the air, on land, and at sea.'
The former four-star Marine Corps general, whose last day is Monday, announced his resignation in late December with a letter saying his views were not aligned with those of President Donald Trump, who had just announced plans to withdraw US troops from Syria.
'Because you have the right to have a Secretary of Defense whose views are better aligned with yours on these and other subjects, I believe it is right for me to step down from my position,' Mattis wrote in his letter to the President.
On Monday, the Pentagon will hold a government-wide call between Mattis and Shanahan to mark the transition of power.
A defense official said the call is meant 'to ensure all members within the government know who is in command' and is 'a courtesy and a mark of respect for the incoming Secretary of Defense.'
A former corporate executive, Shanahan's portfolio at the Department of Defense has been narrow, with no experience in international affairs or counterterrorism. As Mattis' No. 2 in the Pentagon, Shanahan almost exclusively handled internal reform, budget issues and the Space Force, the new military branch proposed by Trump.