Often called the “Father of Europe,” Charlemagne was a Frankish warrior king who united much of the continent under the banner of the Carolingian Empire. Beginning in the late 700s, Charlemagne forged a vast kingdom through extensive military campaigns against the Saxons, the Lombards and the Avars. A devout Catholic, he also aggressively converted his subjects to Christianity and instituted strict religious reforms.

On Christmas Day 800, Pope Leo III crowned Charlemagne “emperor of the Romans” during a ceremony at St. Peter’s Basilica. This controversial coronation restored the Western Roman Empire in name and established Charlemagne as the divinely appointed leader of most of Europe. More importantly, it placed him on equal footing with the Byzantine Empress Irene, who ruled over the Eastern Empire in Constantinople. Charlemagne would serve as emperor for 13 years, and his legal and educational reforms sparked a cultural revival and unified much of Europe for the first time since the fall of the Roman Empire.

The 1066 holiday season played host to an event that permanently changed the course of European history. On Christmas Day, William, Duke of Normandy—better known as William the Conqueror—was crowned king of England at Westminster Abbey in London. This coronation came in the wake of William’s legendary invasion of the British Isles, which ended in October 1066 with a victory over King Harold II at the Battle of Hastings.

William the Conqueror’s 21-year rule would see many Norman customs and laws find their way into English life. After consolidating his power by building famous structures such as the Tower of London and Windsor Castle, William also gave copious land grants to his French-speaking allies. This not only permanently changed the development of the English language—nearly one-third of modern English is derived from French words—but it also contributed to the rise of the feudal system of government that characterized much of the Middle Ages.

At the end of 1776, the Revolutionary War looked like it might be lost for colonial forces. A series of defeats by the British depleted morale, and many soldiers deserted the Continental Army. Desperate to strike a decisive victory, on Christmas Day General George Washington led 2,400 troops on a daring nighttime crossing of the icy Delaware River. Stealing into New Jersey, on December 26 the Continental forces launched a surprise attack on Trenton, which was held by a force of German soldiers known as Hessians.

General Washington’s gamble paid off. Many of the Hessians were still disoriented from the previous night’s holiday bender, and colonial forces defeated them with minimal bloodshed. While Washington had pulled off a shock victory, his army was unequipped to hold the city and he was forced to re-cross the Delaware that same day—this time with nearly 1,000 Hessian prisoners in tow. Washington would go on to score successive victories at the Battles of the Assunpink Creek and Princeton, and his audacious crossing of the frozen Delaware served as a crucial rallying cry for the beleaguered Continental Army.

On December 24, 1814, while many in the western world celebrated Christmas Eve, the United States and Great Britain sat down to sign a famous peace agreement ending the War of 1812. Negotiations had begun in Ghent, Belgium, earlier that August—the same month that British forces burned the White House and the U.S. Capitol in Washington. After more than four months of debate, the American and British delegations agreed to a settlement that essentially ended the war as a draw. All conquered territories were relinquished, and captured soldiers and vessels were returned to their respective nations.

While the Treaty of Ghent effectively ended the 32-month conflict, it did not take effect in the United States until it was ratified in February 1815. In fact, one of the greatest American victories of the war—at the Battle of New Orleans in January 1815—came more than a week after the Treaty of Ghent had been signed.

At the tail end of his term as president, Andrew Johnson gave a handful of former Confederate rebels a famous Christmas present. By way of Proclamation 179, on December 25, 1868, Johnson issued an amnesty to “all and every person” who had fought against the United States during the Civil War.

Johnson’s blanket pardon was actually the fourth in a series of postwar amnesty orders dating back to May 1865. Earlier agreements had restored legal and political rights to Confederate soldiers in exchange for signed oaths of allegiance to the United States, but these pardons exempted 14 classes of people including certain officers, government officials and those with property valued over $20,000. The Christmas pardon stood as a final and unconditional act of forgiveness for unreconstructed Southerners, including many former Confederate generals.

The year 1914 saw the Christmas spirit manifest itself in the most unlikely of places-a World War I battlefield. Starting on the evening of December 24, scores of German, British and French troops in Belgium laid down their arms and initiated a spontaneous holiday ceasefire. The truce was reportedly instigated by the Germans, who decorated their trenches with Christmas trees and candles and began singing carols like “Silent Night.” British troops responded with their own rendition of “The First Noel,” and the weary combatants eventually ventured into “no man’s land”—the treacherous, bombed-out space that separated the trenches—to greet one another and shake hands.

According to accounts from the men involved, the soldiers shared cigarettes and pulls of whiskey, and some exchanged Christmas presents with men they had been shooting at only hours before. Taking advantage of the brief lull in combat, some Scottish, English and German troops even played a pick-up game of soccer on the frozen battlefield. The truce was not sanctioned by the officers on either side, and eventually, the men were called back to their respective trenches to resume fighting. Later attempts at holiday meetings were mostly forbidden, but as the war dragged on the “Christmas Truce” would stand as a remarkable example of shared humanity and brotherhood on the battlefield.

As part of 1968’s Apollo 8 mission, astronauts Frank Borman, Jim Lovell and William Anders spent the night before Christmas orbiting the moon. The operation was originally planned to test out the lunar module—later used in the Apollo 11 moon landing—in Earth’s orbit. But when work on the module fell behind schedule, NASA ambitiously changed the mission plan to a lunar voyage. Apollo 8 went on to result in a series of breakthroughs for manned space flight: The three astronauts became the first men to leave Earth’s gravitational pull, the first to orbit the moon, the first to view all of Earth from space and the first to see the dark side of the moon.

Apollo 8 is perhaps best remembered today for the broadcast the three astronauts made when they entered the moon’s orbit on Christmas Eve. As viewers were shown pictures of the moon and Earth from lunar orbit, Borman, Lovell and Anders read the opening lines of the book of Genesis from the Bible. The broadcast—which ended with the famous line “Merry Christmas, and God bless all of you, all of you on the good Earth”—became one of the most watched television events in history.