December 18 in Military History

The Continental Congress proclaimed a national day of thanksgiving following the American victory at Saratoga, the battle that convinced France to enter the war on the American side. General Washington observed the day at Valley Forge, where his army was about to begin its legendary winter encampment.

New Jersey became the third state to ratify the United States Constitution, following Delaware and Pennsylvania. The unanimous 38-to-0 vote of the New Jersey ratifying convention confirmed the small state's support for the federal structure negotiated at Philadelphia, in which the Great Compromise had preserved equal Senate representation for small states against the population-based House.

Secretary of State William Seward officially proclaimed the ratification of the Thirteenth Amendment to the Constitution, permanently abolishing slavery in the United States. The amendment was the constitutional capstone of the Union's Civil War victory and the sacrifice of more than 360,000 Union soldiers who died to preserve the nation and end human bondage.

Tchaikovsky's ballet The Nutcracker premiered at the Mariinsky Theatre in St. Petersburg. While a cultural rather than purely military event, the ballet became a Cold War-era staple of American touring companies whose exchanges with Soviet cultural institutions formed one of the few consistent channels of soft-power contact between the superpowers during decades of military standoff.

The Battle of Verdun on the Western Front ended after ten months of continuous combat, with French forces having recovered nearly all the ground they had lost to the initial German offensive launched in February. The battle produced roughly 700,000 French and German casualties and became the defining symbol of industrial-age attritional warfare.

Adolf Hitler signed Führer Directive No. 21, the operational order for Operation Barbarossa, the invasion of the Soviet Union. The directive called for the Wehrmacht to "crush Soviet Russia in a rapid campaign" before the end of the war against England. The resulting invasion on June 22, 1941, would become the largest military operation in history and the decisive theater of World War II.

The U.S. Supreme Court upheld the constitutionality of Executive Order 9066 in a 6-3 decision, ruling that the wartime internment of 120,000 Japanese Americans was justified by "military necessity." The decision, one of the most criticized in Supreme Court history, was effectively repudiated in 2018 when Chief Justice Roberts wrote that "Korematsu was gravely wrong the day it was decided."

Japan was formally admitted to the United Nations, completing its reentry into the international system eleven years after its surrender in World War II. The admission marked a turning point in the Cold War balance in East Asia, confirming Japan's alignment with the Western bloc and cementing the U.S.-Japan Security Treaty that had reshaped Pacific military strategy since 1951.

U.S. Seventh Air Force and Navy Task Force 77 aircraft struck airfields, surface-to-air missile sites, and petroleum storage facilities in North Vietnam during Operation Proud Deep Alpha, a five-day operation conducted in response to North Vietnamese buildups near the Demilitarized Zone. The strikes were the largest American air operation against the North since the 1968 bombing halt and previewed the operational patterns used during Linebacker I and Linebacker II the following year.

President Nixon ordered the most intensive bombing campaign of the Vietnam War, Operation Linebacker II, sending waves of B-52 Stratofortress bombers against military and industrial targets in Hanoi and Haiphong. Over the next eleven days, more than 200 B-52s flew 730 sorties and dropped over 20,000 tons of ordnance, making it the largest heavy bomber operation since World War II. Fifteen B-52s were shot down and 33 airmen killed.