Dec. 31 (UPI) -- Outgoing Defense Secretary James Mattis told department staff to maintain faith in the country in a farewell message on Monday.
Mattis' final day as secretary was Monday. He resigned earlier this month, with plans to remain until February, but President Donald Trump asked him to leave as of Dec. 31.
Matti's resignation was prompted by Trump's surprise decision on Dec. 19 to withdraw U.S. troops from Syria. Mattis announced his resignation the next day.
"You have a right to have a secretary of defense whose views are better aligned with yours," Mattis, a retired four-star general, wrote in his resignation letter to Trump.
It reads, in full:
"On Feb. 1, 1865, President Lincoln sent to Gen. Ulysses S. Grant a one-sentence telegram. It read: 'Let nothing which is transpiring, change, hinder, or delay your military movements, or plans.'
"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. Our department is proven to be at its best when the times are most difficult. So keep the faith in our country and hold fast, alongside our allies, aligned against our foes.
"It has been my high honor to serve at your side. May God hold you safe in the air, on land and at sea."