Just one day before turning in his resignation, Defense Secretary Jim Mattis taped a holiday message to his entire department.

The video, dated Dec. 19, shows Mattis before a wall of flags, praising U.S. forces for serving the country on a day many Americans take off from work.

“Since Washington crossed the Delaware at Christmas in 1776, American troops have missed holidays at home to defend our experiment in democracy,” he says. “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.”

By Dec. 20, Mattis announced he would be stepping down from his White House post, protesting President Donald Trump’s move to pull troops out of Syria and emphasizing his differences with the commander in chief over his friendliness toward authoritarian regimes.

On Christmas Eve, the Department of Defense tweeted out a holiday letter from Mattis to the military, which again praised troops for “keeping watch by night” during the season, noting they “carry on the proud legacy of those who stood the watch in decades past.”

“Storm clouds loom, yet because of you your fellow citizens live safe at home,” he wrote. “Most don’t know your names but all are confident their freedoms and their families will be kept safe.”

#SecDef Mattis’s Holiday Letter to the Troops pic.twitter.com/xiwcpMpC4q — U.S. Dept of Defense (@DeptofDefense) December 25, 2018

Although Mattis was expected to make his departure from the administration by the end of February, Trump indicated on Sunday that he would be pushed out early, tweeting Deputy Defense Secretary Patrick Shanahan will become the acting defense secretary on Jan. 1.