The World Wars & Cold War
Events · 78
- June 28, 1914World War I
The Assassination of Archduke Franz Ferdinand
Archduke Franz Ferdinand, heir to the throne of Austria-Hungary, and his wife Sophie were shot dead in Sarajevo by Gavrilo Princip, a 19-year-old Bosnian Serb nationalist. The killing came after an earlier bomb attempt failed and the couple's car took a wrong turn.
Reputable source - July–August 1914World War I
The July Crisis and the Outbreak of War
Backed by Germany, Austria-Hungary declared war on Serbia on 28 July. Europe's alliance system pulled in the great powers within days: Germany declared war on Russia on 1 August and on France on 3 August.
Reputable source - August 4, 1914World War I
Germany Invades Belgium
Following the Schlieffen Plan — Germany's strategy to knock out France quickly before turning east against Russia — German armies invaded neutral Belgium on 4 August to outflank the French defenses. The violation of Belgian neutrality brought Britain and its empire into the war that same day.
Reputable source · 2 sources - August 26–30, 1914World War I
The Battle of Tannenberg
On the Eastern Front, a Russian invasion of German East Prussia ended in disaster at Tannenberg, where German forces under Hindenburg and Ludendorff encircled and destroyed the Russian Second Army, taking tens of thousands of prisoners.
Reputable source · 2 sources - September 6–12, 1914World War I
The First Battle of the Marne
A French and British counterattack halted the German advance on Paris in the 'Miracle of the Marne.' The Germans fell back to the River Aisne and dug in; both sides then extended their trench lines to the sea.
Reputable source - December 1914World War I
The Christmas Truce
Along parts of the Western Front, an unofficial and spontaneous truce broke out at Christmas 1914. British and German soldiers left their trenches to meet in no man's land, exchanging gifts, burying the dead, and in places playing impromptu football. It was not observed everywhere, and fighting continued in other sectors.
Reputable source - April 22, 1915World War I
Poison Gas at the Second Battle of Ypres
At the Second Battle of Ypres, German forces released chlorine gas along a stretch of the Allied line — the first large-scale use of a lethal chemical weapon in the war. The gas broke the line held by French and Algerian troops, but Canadian units helped prevent a decisive breakthrough.
Reputable source - 1915–1916World War I
The Armenian Genocide
Beginning with the arrest of Armenian leaders in Constantinople on 24 April 1915, Ottoman authorities carried out the systematic destruction of the empire's Armenian population through massacres, death marches, starvation, and deportation. Of roughly 1.5 million Armenians in the empire, at least 664,000 and possibly up to 1.2 million were killed.
Reputable source - April 1915 – January 1916World War I
The Gallipoli Campaign
Allied troops, including the Australian and New Zealand Army Corps (ANZAC), landed on the Gallipoli peninsula on 25 April 1915, aiming to force the Dardanelles and knock the Ottoman Empire out of the war. The campaign bogged down into months of costly stalemate and ended in an Allied evacuation by January 1916.
Reputable source · 2 sources - May 7, 1915World War I
The Sinking of the Lusitania
The German submarine U-20 torpedoed the British ocean liner RMS Lusitania off the coast of Ireland without warning. The ship sank in under twenty minutes; of nearly 2,000 aboard, some 1,200 died, including 128 American citizens.
Reputable source - February–December 1916World War I
The Battle of Verdun
The German chief of staff Erich von Falkenhayn launched a massive offensive against the French fortress city of Verdun, intending to 'bleed France white' in a battle of attrition. Over ten months the fighting killed or wounded hundreds of thousands on each side; the French held, and the German plan failed.
Reputable source - May 31 – June 1, 1916World War I
The Battle of Jutland
The largest naval battle of the war pitted the British Grand Fleet against the German High Seas Fleet in the North Sea. In a confused, bloody action, Britain lost more ships and men, but the German fleet retreated and never again seriously challenged British control of the seas — so both sides claimed victory.
Reputable source - July 1 – November 18, 1916World War I
The Battle of the Somme
The British-led offensive on the Somme opened on 1 July 1916 with the bloodiest day in the history of the British Army — around 57,000 casualties in a single day. The battle ground on for months for limited gains, and it saw the first-ever use of tanks in war in September 1916.
Reputable source - January 1917World War I
The Zimmermann Telegram
German Foreign Secretary Arthur Zimmermann sent a coded telegram proposing a military alliance with Mexico against the United States, offering to help Mexico regain territory in Texas, New Mexico, and Arizona. British codebreakers intercepted and decoded it and passed it to Washington; its publication in March 1917 inflamed American opinion.
Primary source - April 6, 1917World War I
The United States Enters the War
Provoked by Germany's resumption of unrestricted submarine warfare and the Zimmermann Telegram, the United States declared war on Germany on 6 April 1917. President Woodrow Wilson framed American intervention as a way to shape a lasting peace.
Reputable source - July–November 1917World War I
The Battle of Passchendaele
The Third Battle of Ypres, known as Passchendaele, was a British offensive that aimed to break out of the Ypres salient. Heavy rain turned the battlefield into a sea of mud; over more than three months the Allies advanced about five miles at a cost of some 250,000 casualties.
Reputable source - November 2, 1917World War I
The Balfour Declaration
In a letter to Lord Rothschild, British Foreign Secretary Arthur Balfour declared that the government viewed 'with favour the establishment in Palestine of a national home for the Jewish people,' while pledging that nothing should prejudice the rights of the existing non-Jewish communities there.
Primary source - March & November 1917World War I
The Russian Revolution
In 1917 Russia was convulsed by two revolutions: the February Revolution forced Tsar Nicholas II to abdicate, and in the October (November) Revolution the Bolsheviks under Lenin seized power. The new Soviet government sought to pull Russia out of the war.
Reputable source · 2 sources - January 8, 1918World War I
Wilson's Fourteen Points
In an address to Congress, President Woodrow Wilson set out Fourteen Points as a basis for a just and lasting peace — including open diplomacy, freedom of the seas, self-determination for peoples, and a general association of nations to guarantee security.
Reputable source - March 3, 1918World War I
The Treaty of Brest-Litovsk
Soviet Russia signed the Treaty of Brest-Litovsk with the Central Powers, formally withdrawing from the war. The terms were harsh: Russia surrendered vast western territories, including present-day Poland, the Baltic states, and Ukraine.
Reputable source - March–July 1918World War I
The German Spring Offensive
Reinforced by troops freed from the Eastern Front, General Ludendorff launched a series of massive offensives beginning on 21 March 1918, hoping to win the war before American forces arrived in strength. The Germans made dramatic gains but outran their supplies and could not deliver a knockout blow.
Reputable source - July–August 1918World War I
The Second Battle of the Marne
The last great German offensive of the war was halted near the Marne, and a powerful Allied counterattack — bolstered by fresh American troops — threw the Germans back. It marked the turning of the tide on the Western Front.
Reputable source - August – November 1918World War I
The Hundred Days Offensive
Beginning with the Battle of Amiens on 8 August 1918 — which Ludendorff called the 'black day of the German Army' — the Allies launched a series of coordinated offensives that broke through German defenses and drove the enemy into headlong retreat.
Reputable source - 1918–1919World War I
The 1918 Influenza Pandemic
As the war ended, an exceptionally deadly influenza pandemic — the 'Spanish flu' — swept the world, spread in part by the movement of troops. It infected roughly a third of the global population and killed an estimated 50 million or more people, with about 675,000 deaths in the United States.
Primary source · 2 sources - November 11, 1918World War I
The Armistice
Germany signed an armistice with the Allies in a railway carriage at Compiègne, France. The guns of the Western Front fell silent at 11 a.m. on 11 November 1918 — the eleventh hour of the eleventh day of the eleventh month.
Reputable source - June 28, 1919World War I
The Treaty of Versailles
At the Paris Peace Conference, the victorious 'Big Four' — the United States, Britain, France, and Italy — dominated the drafting of the Treaty of Versailles. Germany was forced to accept strict terms: loss of territory and colonies, disarmament, reparations, and a 'war guilt' clause. The treaty also created the League of Nations. Germany signed on 28 June 1919, five years to the day after the Sarajevo assassination.
Reputable source - July 7, 1937World War II
The Second Sino-Japanese War Begins
A clash between Japanese and Chinese troops at the Marco Polo Bridge (Lugou Bridge) near Beijing escalated within weeks into a full-scale Japanese invasion of China. Following the Battle of Shanghai, Japanese forces captured the Nationalist capital of Nanjing later that year.
Reputable source - September 30, 1938World War II
The Munich Agreement
Germany, Italy, Britain, and France signed the Munich Agreement, forcing Czechoslovakia — which was not party to the talks — to cede its German-speaking Sudetenland border region to Nazi Germany. British Prime Minister Neville Chamberlain and French Premier Édouard Daladier accepted Hitler's demands in the belief they had preserved peace.
Reputable source · 2 sources - August 23, 1939World War II
The Nazi-Soviet Pact
German Foreign Minister Joachim von Ribbentrop and Soviet Foreign Minister Vyacheslav Molotov signed a ten-year nonaggression pact. A secret protocol divided eastern Europe into German and Soviet spheres of influence and agreed to partition Poland.
Reputable source - September 1, 1939World War II
Germany Invades Poland
Germany launched an unprovoked invasion of Poland at dawn, spearheaded by tanks and aircraft. Britain and France declared war on Germany on September 3. Warsaw fell at the end of September, and the Soviet Union invaded from the east on September 17.
Reputable source - May–June 1940World War II
The Fall of France and the Dunkirk Evacuation
On May 10, 1940, Germany's blitzkrieg swept through the Low Countries and into France, bypassing the Maginot Line. As Allied armies collapsed, Operation Dynamo evacuated more than 338,000 British and French troops from the beaches of Dunkirk between May 26 and June 4. Germany entered Paris on June 14, and France signed an armistice on June 22.
Reputable source · 2 sources - July–October 1940World War II
The Battle of Britain
Germany's Luftwaffe fought to win air superiority over southern England in preparation for an invasion. RAF Fighter Command, flying Hurricanes and Spitfires and aided by a pioneering radar-based air-defense network, denied the Germans control of the skies. Hitler ultimately postponed the invasion.
Reputable source · 2 sources - June 22, 1941World War II
Operation Barbarossa: Germany Invades the Soviet Union
Germany launched Operation Barbarossa, invading the Soviet Union with roughly three million Axis troops along a vast front — the largest military operation in history. The attack broke the 1939 Nazi-Soviet Pact and opened the Eastern Front.
Reputable source - December 7, 1941World War II
The Attack on Pearl Harbor
In a surprise attack, 353 aircraft from six Japanese carriers struck the U.S. Pacific Fleet at Pearl Harbor, Hawaii, in two waves. They sank or damaged numerous battleships and destroyed many aircraft; more than 2,400 Americans were killed. The U.S. aircraft carriers were at sea and escaped.
Reputable source · 2 sources - January 20, 1942World War II
The Wannsee Conference and the 'Final Solution'
Fifteen senior Nazi and German government officials met at a villa on Berlin's Lake Wannsee to coordinate the 'Final Solution to the Jewish Question' — the systematic murder of Europe's Jews. Reinhard Heydrich outlined a plan encompassing some 11 million Jews across Europe and assigned the SS to lead the killing.
Reputable source - June 4–7, 1942World War II
The Battle of Midway
Forewarned by code-breaking, U.S. carrier forces ambushed a Japanese fleet advancing on Midway Atoll. American dive-bombers sank all four of Japan's fleet carriers in the engagement, at the cost of the carrier USS Yorktown.
Reputable source · 2 sources - October 23 – November 11, 1942World War II
The Second Battle of El Alamein
In the Egyptian desert, General Bernard Montgomery's British Eighth Army launched a set-piece offensive against the Axis forces of Erwin Rommel, opening with a massive artillery barrage on the night of October 23. After nearly two weeks of grinding attrition, the Axis line broke and Rommel was driven into a long retreat westward.
Reputable source · 2 sources - August 1942 – February 2, 1943World War II
The Battle of Stalingrad Ends
After months of brutal urban fighting, a Soviet counteroffensive encircled the German Sixth Army in Stalingrad. Cut off and starving, Field Marshal Friedrich Paulus surrendered the trapped force; roughly 91,000 survivors were taken prisoner when resistance ended on February 2, 1943.
Reputable source · 2 sources - July–September 1943World War II
The Allied Invasion of Italy and the Fall of Mussolini
The Allies landed in Sicily on July 10, 1943 (Operation Husky). Amid the collapse, Benito Mussolini was deposed and arrested on July 25. The new Italian government under Marshal Pietro Badoglio secretly negotiated an armistice, announced on September 8. German forces then occupied much of Italy and fought on there for the rest of the war.
Reputable source - June 6, 1944World War II
D-Day: The Normandy Landings
Operation Overlord, the largest amphibious invasion in history, put nearly 160,000 Allied troops ashore across five Normandy beaches — code-named Utah, Omaha, Gold, Juno, and Sword — supported by thousands of ships and aircraft under the command of General Dwight D. Eisenhower.
Reputable source · 2 sources - August 25, 1944World War II
The Liberation of Paris
As Allied armies broke out of Normandy and the French Resistance rose within the city, General Philippe Leclerc's Free French 2nd Armored Division and U.S. troops entered Paris. The German garrison surrendered, and General Charles de Gaulle walked down the Champs-Élysées in triumph.
Reputable source - October 23–26, 1944World War II
The Battle of Leyte Gulf
Fought in the waters around the Philippines across four major engagements, Leyte Gulf was the largest naval battle of World War II. The U.S. Navy shattered the Imperial Japanese Navy's remaining offensive strength; the battle also saw the first organized kamikaze attacks.
Reputable source - December 16, 1944 – January 1945World War II
The Battle of the Bulge
Germany launched a surprise winter offensive through the forested Ardennes, aiming to split the Allied armies and reach the port of Antwerp. The attack created a large 'bulge' in the Allied line but was halted and then reversed; by late January 1945 the Allies had retaken all the lost ground.
Reputable source - January 27, 1945World War II
The Liberation of Auschwitz
Soviet troops entered the Auschwitz camp complex in occupied Poland and freed roughly 7,000 prisoners left behind — many starving and gravely ill — after the SS had forced tens of thousands of others on death marches westward. Auschwitz-Birkenau had been the largest of the Nazi killing centers.
Reputable source - February 4–11, 1945World War II
The Yalta Conference
With Germany near defeat, the 'Big Three' — Franklin Roosevelt, Winston Churchill, and Joseph Stalin — met in the Crimean resort of Yalta to plan the war's end and the postwar order. They discussed the occupation of Germany, the future of eastern Europe and a new United Nations, and agreed the Soviet Union would enter the war against Japan.
Reputable source - April 1 – June 22, 1945World War II
The Battle of Okinawa
U.S. Tenth Army forces landed on Okinawa on April 1, 1945, in the largest amphibious assault of the Pacific war. Nearly three months of ferocious fighting and mass kamikaze attacks killed tens of thousands of soldiers on both sides and enormous numbers of Okinawan civilians.
Reputable source - April 30 – May 2, 1945World War II
The Fall of Berlin and Hitler's Death
As the Red Army fought through Berlin, Adolf Hitler killed himself in his bunker on April 30, 1945, alongside Eva Braun, whom he had married the day before. Berlin's defenders surrendered to Soviet forces on May 2.
Reputable source · 2 sources - May 8, 1945World War II
V-E Day: Victory in Europe
Germany surrendered unconditionally. General Alfred Jodl signed the surrender at Eisenhower's headquarters in Reims on May 7; a second signing followed in Berlin. The Western Allies proclaimed May 8 as Victory in Europe Day, and crowds celebrated in cities across the world.
Reputable source - June 26, 1945World War II
The United Nations Is Founded
Delegates of 50 nations, meeting at the San Francisco Conference, signed the Charter of the United Nations on June 26, 1945. The Charter entered into force on October 24, 1945, establishing a new international organization to maintain peace and security.
Reputable source · 2 sources - August 6 & 9, 1945World War II
The Atomic Bombings of Hiroshima and Nagasaki
On August 6, 1945, the American B-29 Enola Gay dropped the uranium bomb 'Little Boy' on Hiroshima; three days later, on August 9, Bockscar dropped the plutonium bomb 'Fat Man' on Nagasaki. Each bomb destroyed most of its city and killed tens of thousands of people instantly, with many more dying later from injuries and radiation.
Reputable source · 3 sources - September 2, 1945World War II
Japan Surrenders: V-J Day
Following the atomic bombings and the Soviet declaration of war, Japan agreed to surrender. Japanese and Allied representatives signed the Instrument of Surrender aboard the battleship USS Missouri in Tokyo Bay on September 2, 1945, with General Douglas MacArthur presiding.
Reputable source · 2 sources - November 20, 1945World War II
The Nuremberg Trials Begin
The International Military Tribunal opened at Nuremberg, where the United States, Britain, the Soviet Union, and France jointly prosecuted senior Nazi leaders. Twenty-four defendants were indicted on charges including crimes against peace, war crimes, and crimes against humanity.
Reputable source - March 5, 1946The Cold War
Churchill's 'Iron Curtain' Speech
At Westminster College in Fulton, Missouri, with President Truman present, Winston Churchill delivered his 'Sinews of Peace' address, warning that 'from Stettin in the Baltic to Trieste in the Adriatic, an iron curtain has descended across the Continent,' dividing Soviet-dominated Eastern Europe from the West.
Reputable source - March 12, 1947The Cold War
The Truman Doctrine
In a speech to Congress, President Harry Truman pledged that the United States would 'support free peoples who are resisting attempted subjugation by armed minorities or by outside pressures,' beginning with aid to Greece and Turkey.
Reputable source - 1947–1948The Cold War
The Marshall Plan
Proposed by Secretary of State George Marshall in a June 1947 speech and enacted by Congress in 1948, the European Recovery Program channeled some $13 billion into rebuilding war-torn Western Europe. Aid was offered to all of Europe but rejected by the Soviet Union and its satellites.
Reputable source - June 1948 – May 1949The Cold War
The Berlin Blockade and Airlift
The Soviet Union blockaded road, rail, and water access to the western sectors of Berlin, deep inside Soviet-occupied Germany. The United States and Britain responded with a massive airlift, flying in food and fuel — at its peak, a plane landed roughly every minute — until the Soviets lifted the blockade in May 1949.
Reputable source · 2 sources - April 4, 1949The Cold War
NATO Is Founded
The United States, Canada, and ten Western European nations signed the North Atlantic Treaty in Washington, creating NATO — a collective-security alliance in which an attack on one member would be treated as an attack on all. It was the first peacetime military alliance the United States joined outside the Western Hemisphere.
Reputable source · 2 sources - August 29, 1949The Cold War
The Soviet Union Tests Its First Atomic Bomb
The Soviet Union detonated its first nuclear device — codenamed RDS-1, and dubbed 'Joe-1' in the West — years earlier than most American experts had predicted. President Truman announced the test to a shocked public in September 1949.
Reputable source - October 1, 1949The Cold War
The People's Republic of China Is Founded
After winning the Chinese Civil War against the Nationalists, Communist leader Mao Zedong proclaimed the People's Republic of China in Beijing. The defeated Nationalists fled to Taiwan; the United States refused to recognize the new government.
Reputable source - 1950–1953The Cold War
The Korean War
Communist North Korea invaded the South in June 1950. A United Nations force led by the United States pushed the invaders back, but the intervention of Communist China in late 1950 turned the war into a bloody stalemate near the 38th parallel, ending in an armistice in 1953.
Reputable source · 2 sources - May 14, 1955The Cold War
The Warsaw Pact
In response to West Germany's admission to NATO, the Soviet Union and its Eastern European satellites signed the Warsaw Treaty, creating a rival military alliance. Though nominally a pact of equals, its decisions were controlled by Moscow.
Reputable source - October–November 1956The Cold War
The Hungarian Revolution
A popular uprising in Hungary toppled the Stalinist government, and reformist premier Imre Nagy announced Hungary's withdrawal from the Warsaw Pact. In early November, Soviet tanks crushed the revolt; Nagy was later executed, and tens of thousands of Hungarians fled abroad.
Reputable source - October 4, 1957The Cold War
Sputnik and the Space Race
The Soviet Union launched Sputnik 1, the first artificial satellite to orbit the Earth. The launch stunned Americans, who had assumed their country led in science and technology, and touched off the space race.
Reputable source - April 1961The Cold War
The Bay of Pigs Invasion
After Fidel Castro's 1959 revolution aligned Cuba with the Soviet Union, the United States backed an invasion by CIA-trained Cuban exiles at the Bay of Pigs. The landing was quickly crushed by Castro's forces — a humiliating failure for the new Kennedy administration.
Reputable source - August 13, 1961The Cold War
The Berlin Wall Is Built
To stop the flood of refugees escaping to the West, East Germany, on Soviet orders, sealed the border in Berlin overnight with barbed wire — soon replaced by a concrete wall with guard towers. The Berlin Wall physically divided the city for 28 years.
Reputable source · 2 sources - October 1962The Cold War
The Cuban Missile Crisis
US spy planes discovered Soviet nuclear missile sites under construction in Cuba. President Kennedy imposed a naval 'quarantine' of the island, and for thirteen days the superpowers stood on the brink of nuclear war. The crisis ended when the Soviets agreed to remove the missiles in exchange for a US pledge not to invade Cuba and the secret removal of US missiles from Turkey.
Reputable source - 1964–1973 (US escalation)The Cold War
The Vietnam War and the Gulf of Tonkin
After reported North Vietnamese attacks on US destroyers in the Gulf of Tonkin, Congress passed the Gulf of Tonkin Resolution in August 1964, giving President Johnson broad authority to wage war. The United States escalated massively, eventually deploying over half a million troops before withdrawing in 1973.
Reputable source - August 1968The Cold War
The Prague Spring
Reformist leader Alexander Dubček's attempt to build 'socialism with a human face' in Czechoslovakia alarmed Moscow. On the night of 20–21 August 1968, Warsaw Pact troops invaded and crushed the reforms. The Soviet leadership justified the invasion with the 'Brezhnev Doctrine' — the claim of a right to intervene in any threatened communist state.
Reputable source - February 1972The Cold War
Nixon's Visit to China
President Richard Nixon traveled to Communist China in February 1972, becoming the first sitting US president to do so and meeting with Mao Zedong. The visit, capped by the Shanghai Communiqué, began the normalization of US–China relations after more than two decades of estrangement.
Reputable source - May 26, 1972The Cold War
Détente and the SALT I Treaty
In Moscow, Nixon and Soviet leader Leonid Brezhnev signed the SALT I agreements, including the Anti-Ballistic Missile (ABM) Treaty. For the first time in the Cold War, the superpowers agreed to limit their strategic nuclear arsenals — the centerpiece of the policy of détente.
Reputable source - December 1979The Cold War
The Soviet Invasion of Afghanistan
At the end of December 1979, Soviet troops poured into Afghanistan to prop up a faltering communist government, killing its leader and installing a client in his place. The intervention drew nearly worldwide condemnation and years of guerrilla resistance from US-backed insurgents.
Reputable source - August 1980The Cold War
Solidarity in Poland
A wave of strikes led by electrician Lech Wałęsa at the Gdańsk shipyard forced Poland's communist government to sign the Gdańsk Agreement, allowing the first independent trade union in the Soviet bloc — Solidarity. The government imposed martial law in December 1981, but the movement survived underground.
Primary source - March 23, 1983The Cold War
Reagan's 'Star Wars': The Strategic Defense Initiative
In a televised address, President Ronald Reagan announced the Strategic Defense Initiative (SDI), a research program to build a space-based shield against nuclear missiles. Critics dubbed it 'Star Wars,' and the technology remained largely unrealized.
Reputable source - 1985The Cold War
Gorbachev's Reforms: Glasnost and Perestroika
Mikhail Gorbachev became leader of the Soviet Union in March 1985 and launched reforms to revive the stagnant system: perestroika (economic and political 'restructuring') and glasnost ('openness'). He also sought to ease tensions and reduce the arms burden abroad.
Reputable source - December 8, 1987The Cold War
The INF Treaty
At the White House, Reagan and Gorbachev signed the Intermediate-Range Nuclear Forces (INF) Treaty, which for the first time eliminated an entire class of nuclear weapons — all US and Soviet ground-launched intermediate- and shorter-range missiles — under strict verification.
Primary source - November 9, 1989The Cold War
The Fall of the Berlin Wall
Amid mass peaceful protests across East Germany and a botched announcement of new travel rules, crowds surged to the Berlin Wall on the night of 9 November 1989. Overwhelmed guards opened the gates, and East and West Berliners celebrated atop the Wall. It was the climax of a wave of revolutions that swept away communist governments across Eastern Europe in 1989.
Reputable source · 2 sources - October 3, 1990The Cold War
The Reunification of Germany
Less than a year after the Wall fell, East Germany was absorbed into the Federal Republic on 3 October 1990. Gorbachev, withdrawing Soviet forces, agreed to reunification and accepted that a united Germany could remain in NATO.
Reputable source - December 1991The Cold War
The Dissolution of the Soviet Union
After a failed hardline coup in August 1991 accelerated the Soviet Union's unraveling, the republics declared independence. On 25 December 1991 Gorbachev resigned, the Soviet flag was lowered over the Kremlin, and the USSR formally ceased to exist the next day, leaving Boris Yeltsin's Russia and fourteen other new states.
Reputable source