Outgoing Defense Secretary Jim Mattis reportedly spent Christmas Day working at the Pentagon, with only a week to go before Acting Secretary Patrick Shanahan takes over on January 1, as ordered by President Donald Trump. The Defense Department published the final holiday message to the troops from Mattis on Christmas Eve.

The message from Secretary Mattis, dated December 18 and posted by the Defense Department’s Twitter account on Christmas Eve, read as follows:

We in the U.S. military are privileged to defend America, especially at this time of year, for we ensure our fellow Americans celebrate this season of hope in peace and safety. We know our freedoms are not guaranteed by themselves; they need defenders. This month, many in our military will be serving far from their loved ones. It is difficult work, but this is nothing new; since Washington crossed the Delaware on Christmas Day in 1776, American troops have missed holidays to defend our citizens’ experiment in democracy. To those in the field or at sea, “keeping watch by night” this holiday season, you should recognize that you carry on the proud legacy of those who stood the watch in decades past. In this world awash in change, you hold the line. Storm clouds loom, yet because of you your fellow citizens live safe at home. Most don’t know your names but all are confident their freedoms and their families will be kept safe. Far from home, you have earned the gratitude and respect of your fellow citizens and it remains my great privilege to serve alongside you. Merry Christmas and may God hold you safe.

Mattis delivered a similar message in a brief video recorded shortly before he tendered his resignation, “To all you lads and lasses holding the line in 2018 on land, at sea, or in the air, thanks for keeping the faith. Merry Christmas and may God hold you safe.”

#SecDef Mattis' final holiday message to the DOD: "To all you lads and lasses holding the line in 2018 on land, at sea, or in the air, thanks for keeping the faith. Merry Christmas and may God hold you safe." pic.twitter.com/YIdMaVgIWE — Julio Rosas (@Julio_Rosas11) December 24, 2018

The famously literate Defense Secretary quoted from the Book of Luke in his letter, likening American troops deployed around the world to the shepherds tending their flocks in the fields around Bethlehem on the night Jesus was born:

There were shepherds living out in the fields nearby, keeping watch over their flocks at night. An angel of the Lord appeared to them, and the glory of the Lord shone around them, and they were terrified. But the angel said to them, ‘Do not be afraid. I bring you good news that will cause great joy for all the people. Today in the town of David a Savior has been born to you; he is the Messiah, the Lord. This will be a sign to you: You will find a baby wrapped in cloths and lying in a manger.”

President Trump expounded on his differences with Secretary Mattis on the day before Christmas.

“To those few Senators who think I don’t like or don’t appreciate being allied with other countries, they are wrong, I DO,” Trump wrote on Twitter. “What I don’t like, however, is when many of these same countries take advantage of their friendship with the United States, both in Military Protection and Trade.”

“We are substantially subsidizing the Militaries of many VERY rich countries all over the world, while at the same time these countries take total advantage of the U.S., and our TAXPAYERS, on Trade,” he continued. “General Mattis did not see this as a problem. I DO, and it is being fixed!”