In an unofficial and spontaneous ceasefire, thousands of soldiers on both sides of the Western Front stopped fighting. Troops sang carols, exchanged tobacco, buttons, and food, and in some sectors played impromptu football matches in the frozen mud. Commanders on both sides were alarmed by the fraternization and moved swiftly to prevent it from recurring in later years of the war.

Maulana Karenga, a professor and civil rights activist, created Kwanzaa in the aftermath of the Watts riots as a way to unify and empower African American communities through a celebration of African heritage. Drawing from various African harvest festivals, he built the holiday around seven principles, or Nguzo Saba, observed over seven days from December 26 to January 1, with the first observance beginning informally around this date in 1966.

On their ninth of ten lunar orbits, Apollo 8's crew broadcast live to what was then the largest television audience in history. Each astronaut read verses from the Book of Genesis before signing off with 'good night, good luck, a merry Christmas, and God bless all of you — all of you on the good Earth.' William Anders had captured the iconic 'Earthrise' photograph on this mission, reframing humanity's view of its own planet.

Five days after the United States launched Operation Just Cause to depose Panamanian dictator Manuel Noriega, American forces surrounded the Papal Nunciature where he had sought asylum. U.S. troops blasted rock music at deafening volume around the embassy in a psychological pressure campaign. Noriega, indicted in the U.S. on drug trafficking charges, would hold out until January 3, 1990, before finally surrendering.