World War II, a global conflict that reshaped the 20th century, is a pivotal moment in human history. Understanding how long World War 2 was requires looking at its multifaceted timeline, marked by distinct phases and global engagements. While pinpointing an exact duration is complex due to varying start and end dates across different regions, we can definitively say World War II lasted for approximately six years, from 1939 to 1945.
To fully grasp the length and scope of this monumental war, let’s delve into a detailed timeline of its key events and milestones:
The Beginning of Global Conflict: Precursors and Official Start
While the commonly accepted start date of World War II is September 1, 1939, with Germany’s invasion of Poland, seeds of conflict were sown much earlier. Many historians point to the clash near the Marco Polo Bridge on July 7, 1937, as the true starting point of large-scale hostilities, marking the beginning of the Second Sino-Japanese War, a brutal and protracted conflict that would eventually become intertwined with the global war.
Clash near the Marco Polo Bridge, close to Beijing, 7 July 1937
This incident, seemingly minor at first, ignited the full-scale war between Japan and China. A Japanese unit conducting night maneuvers near the Marco Polo Bridge southwest of Beijing clashed with Chinese forces. This event escalated rapidly as the Japanese military, feeling their honor challenged, deployed reinforcements. Hardliners within the Japanese army seized this opportunity to aggressively pursue their territorial ambitions in China. Meanwhile, Jiang Jieshi, the leader of Nationalist China, was unwilling to appease Japan’s demands. This clash spiraled into a major conflict that significantly weakened both nations. Large-scale fighting erupted towards the end of July, leading to the occupation of Beijing by Japan on July 29. This Sino-Japanese War, lasting until 1945, was a crucial precursor and an integral part of the wider World War II narrative.
1939: The Invasion of Poland and the War in Europe Begins
The German invasion of Poland, 1 September 1939
The date most universally recognized as the start of World War II is September 1, 1939. On this day, Adolf Hitler’s Germany launched a blitzkrieg – “lightning war” – invasion of Poland. Despite valiant Polish resistance, they were overwhelmed by the sheer force and advanced tactics of the German Wehrmacht, particularly the Luftwaffe’s aerial dominance.
Two days later, on September 3, 1939, honoring their treaty obligations to Poland, both France and Great Britain declared war on Germany. However, this declaration did not translate into immediate military assistance for Poland. Adding to Poland’s plight, the Soviet Union invaded eastern Poland two weeks later. By September 27, Warsaw surrendered, and organized Polish resistance crumbled within a week. Poland was then divided between Nazi Germany and the Soviet Union under the Molotov-Ribbentrop Pact.
The Nazi occupation of Poland was brutal, marked by a reign of terror that would ultimately claim six million Polish lives, half of whom were Polish Jews murdered in extermination camps. The Soviet regime in their occupied zone was equally oppressive, exemplified by the Katyn Forest Massacre in March and April 1940, where over 20,000 Polish officers and intellectuals were murdered. Tens of thousands more Poles were forcibly deported to Siberia.
This invasion and subsequent division of Poland officially ignited the war in Europe, setting the stage for years of conflict and global upheaval.
1940: Expansion of the War in Europe and the Battle of Britain
Germans launch offensive in the West, 10 May 1940
Germany’s ambitions extended beyond Poland. On May 10, 1940, the Wehrmacht launched a major offensive in Western Europe, invading neutral Belgium and the Netherlands, and attacking France. The German military strategy of Blitzkrieg, characterized by rapid armored advances supported by air power, proved devastatingly effective. The French and British forces, unprepared for this type of mobile warfare and lacking a cohesive defense-in-depth strategy, were quickly overwhelmed.
Germany’s swift victory in the six-week campaign dramatically shifted the strategic landscape of Europe. This success emboldened Hitler, reinforcing his belief in his own infallibility and the invincibility of the German military. With Western Europe under German control, any future challenge to Nazi Germany would require overcoming this formidable dominance.
The Battle of Britain, 25 July, 1940
Following France’s surrender in June 1940, Britain stood alone against Nazi Germany. Winston Churchill, the newly appointed British Prime Minister, rallied the nation with his powerful speeches, declaring, “Hitler knows that he will have to break us in this island or lose the war.”
To pave the way for a potential invasion of Britain (Operation Sea Lion), Germany needed to achieve air superiority over the English Channel and Southern England. The Battle of Britain began on July 10, 1940, with the German Luftwaffe launching attacks on shipping in the English Channel.
In August, the Luftwaffe shifted its focus to attacking Royal Air Force (RAF) airfields and aircraft factories. Under the leadership of Lord Beaverbrook, British aircraft production, particularly Spitfire and Hurricane fighters, significantly increased. Despite suffering losses in pilots and planes, the RAF was never as weakened as the Germans believed.
Crucially, the Battle of Britain was fought over British soil. RAF pilots who survived being shot down could quickly return to duty, while downed German aircrew became prisoners of war. British radar technology, ground crews, and factory workers played vital roles in the defense. The battle raged until the end of October, but by early September, the Luftwaffe shifted its focus to night bombing, signaling a strategic defeat in their aim to achieve daytime air superiority. This victory, secured by the “few,” as Churchill famously called the RAF pilots, prevented a German invasion of Britain and marked a crucial turning point in the war.
The Blitz, 29 December 1940
Unable to achieve air superiority for invasion, Hitler ordered a shift to strategic bombing of British cities, known as the Blitz, a German term for “lightning war.” While London was accidentally bombed on August 24, 1940, retaliatory British bombing of Berlin prompted the Germans to initiate sustained bombing raids on British towns and cities.
September 7, 1940, “Black Saturday,” marked the start of the major attacks on London. For 57 consecutive nights, the capital was bombed, with over 13,650 tons of high explosives and 12,586 incendiary canisters dropped by the Luftwaffe. Starting with the devastating bombing of Coventry on November 14, 1940, other British cities were also targeted while attacks on London continued.
The Blitz resulted in over 43,000 civilian deaths and widespread destruction, but it failed to break British morale or cripple Britain’s war production capacity. As Churchill stated, Hitler failed to “break our famous island race by a process of indiscriminate slaughter and destruction.”
1941: Expansion into Russia and the Pacific Theater Opens
Operation Barbarossa: the German invasion of Russia, June 1941
Driven by long-held ideological and strategic goals, Hitler launched Operation Barbarossa, the invasion of the Soviet Union, on June 22, 1941. Hitler viewed Russia as the primary target for German expansion, seeking “Lebensraum” (living space) and the destruction of “Jewish Bolshevism.” The non-aggression pact with Stalin in 1939 was merely a temporary strategic maneuver.
Despite repeated warnings, Stalin was caught off guard. In the initial months of the invasion, the Germans achieved stunning victories, capturing vast territories and hundreds of thousands of Soviet prisoners. However, they failed to capture Moscow or Leningrad before the harsh Russian winter set in.
On December 5/6, 1941, the Red Army launched a counter-offensive, pushing back the German forces and removing the immediate threat to Moscow. This counter-offensive brought the German military to the brink of a catastrophic crisis and marked the failure of the initial Blitzkrieg strategy in the East.
Pearl Harbor, 7 December 1941
In Asia, tensions between Japan and the United States were escalating. Following Japan’s occupation of French Indochina in July 1941, the US, along with Britain and the Netherlands, imposed economic sanctions, freezing Japanese assets. Many in Japan believed war with the US and European colonial powers was unavoidable to secure vital resources.
In October 1941, a hardline government under General Hideki Tojo came to power, and plans for a surprise attack on the United States were finalized.
On December 7, 1941, a date President Roosevelt declared “will live in infamy,” Japanese carrier-based aircraft launched a surprise attack on the US Pacific Fleet at Pearl Harbor in Hawaii. Despite warnings, the attack caught the Americans completely unprepared. Eight battleships were disabled, and several other warships were damaged or sunk. Over 2,500 Americans were killed.
The attack on Pearl Harbor galvanized American public opinion. The following day, December 8, 1941, the United States Congress declared war on Japan. Germany and Italy, Japan’s Axis allies, declared war on the United States on December 11, 1941, transforming the war into a truly global conflict. Initially, Japan achieved widespread victories across the Pacific, but Admiral Isoroku Yamamoto, the architect of the Pearl Harbor attack, presciently warned, “We can run wild for six months or a year, but after that I have utterly no confidence.”
1942: Turning Points in the Pacific and North Africa
The fall of Singapore, 15 February 1942
Following Pearl Harbor, Japan launched offensives across Southeast Asia. The invasion of Malaya began on December 8, 1941, and British and Commonwealth forces were quickly forced into retreat. The sinking of the British battleships HMS Prince of Wales and Repulse by Japanese aircraft further demoralized the defenders.
Singapore, considered an impregnable fortress, fell to the Japanese on February 15, 1942. British commander Lieutenant General Arthur Percival surrendered over 130,000 troops to a smaller Japanese force. Churchill described the surrender as “the worst disaster… in British military history.” The fall of Singapore was a humiliating defeat and a major blow to British prestige in Asia.
Midway, 4 June 1942
For six months after Pearl Harbor, Japan enjoyed uninterrupted success in the Pacific. However, the tide began to turn at the Battle of Midway, fought on June 4, 1942. Japan aimed to lure the remaining US aircraft carriers into a decisive battle and occupy Midway Atoll to extend their defensive perimeter and force the US to negotiate peace.
However, US Navy codebreakers had deciphered Japanese naval codes, allowing Admiral Chester Nimitz to anticipate the Japanese plan and lay a trap. In the ensuing battle, the US Navy inflicted a crushing defeat on the Japanese fleet, sinking four Japanese aircraft carriers while losing only one US carrier. The Battle of Midway is widely considered the turning point of the Pacific War, shifting the strategic initiative to the Americans. Admiral Nimitz attributed the victory to “Essentially a victory of intelligence,” and President Roosevelt hailed it as “Our most important victory in 1942… there we stopped the Japanese offensive.”
Alamein, 25 October 1942
In North Africa, the war had been a seesaw battle since 1940. By the summer of 1942, German and Italian forces under Field Marshal Erwin Rommel threatened to break through to Cairo and the Suez Canal. The British Eighth Army halted Rommel’s advance at El Alamein, but Churchill replaced the commander with General Harold Alexander and appointed Lieutenant-General Bernard Montgomery to command the Eighth Army.
Montgomery meticulously built up a significant numerical and material advantage before launching his offensive at El Alamein on October 23, 1942. By early November, Axis forces were in full retreat. While final victory in North Africa was not achieved until May 1943, the Battle of El Alamein was a decisive turning point. Churchill famously declared, “…it may almost be said, ‘Before Alamein we never had a victory. After Alamein, we never had a defeat.'”
1943: Stalingrad and Kursk – The Eastern Front Turns
Stalingrad, February 1943
The Battle of Stalingrad, a brutal and pivotal clash on the Eastern Front, began in late August 1942. By September, German forces had reached the suburbs of the city. Stalingrad, named after the Soviet leader, held immense symbolic and strategic importance.
Under General Vasily Chuikov, the Red Army fiercely defended Stalingrad, contesting every street and building. This tenacious defense bought time for General Georgy Zhukov to prepare a massive counter-offensive, launched on November 19, 1942, which encircled the German Sixth Army.
Hitler, against military advice, ordered the Sixth Army to stand fast and refused to allow a retreat. Despite Luftwaffe promises of resupply, the Sixth Army was trapped and starved. On January 31, 1943, General Friedrich Paulus, commander of the Sixth Army, surrendered. Of the 91,000 German soldiers captured, fewer than 6,000 would survive Soviet captivity. Stalingrad was a catastrophic defeat for Germany, marking the beginning of the Soviet advance westward and the turning point on the Eastern Front.
Germans launch the battle of Kursk
In a desperate attempt to regain the initiative on the Eastern Front, the Germans launched a major offensive at Kursk in July 1943. Hitler envisioned a decisive victory that would shatter Soviet forces and potentially weaken the Allied coalition.
However, the Soviets anticipated the attack and prepared massive defensive lines. The Battle of Kursk, which included the largest tank battle in history, began on July 5, 1943. After heavy fighting and significant losses, the German offensive stalled and failed to achieve a breakthrough. On July 13, 1943, Hitler called off the offensive. Kursk was the last major German offensive on the Eastern Front. Following Kursk, the Red Army launched a series of counter-offensives, driving the Germans westward in a near-continuous retreat.
1944: D-Day and the Liberation of Europe Begins
D-Day, Operation Overlord, 6 June 1944
After years of planning and preparation, Operation Overlord, the Allied invasion of Normandy, France, commenced on June 6, 1944, known as D-Day. Under the supreme command of US General Dwight D. Eisenhower, British, American, and Canadian forces landed on five beaches along the Normandy coast, supported by massive naval and air power.
Despite fierce German resistance, particularly on Omaha Beach, the landings were successful. By the end of D-Day, over 158,000 Allied troops were ashore. However, the advance inland was slow and costly, with fierce fighting in the Normandy bocage. The Allied breakout from the beachhead was painstakingly slow. Despite setbacks like the failure of Operation Market Garden at Arnhem, the Allied forces pressed forward. Paris was liberated on August 25, 1944, and Brussels on September 3, 1944. Hopes for a swift end to the war in Europe in 1944 were dashed by the German Ardennes Offensive in December, also known as the Battle of the Bulge. German forces in Northwest Europe finally surrendered to Field Marshal Montgomery on May 4, 1945, at Lüneburg Heath.
23–26 October 1944: Battle of Leyte Gulf
In the Pacific, the US forces began their reconquest of the Philippines in October 1944. This led to the Battle of Leyte Gulf, fought from October 23-26, 1944, the largest naval battle in World War II. The battle was a series of engagements that secured American naval supremacy in the Western Pacific and effectively crippled the Japanese fleet.
The Japanese Operation Sho-Go aimed to lure away the US carrier fleet and attack the vulnerable American landing forces. Despite some initial successes, Japanese naval forces were ultimately defeated, losing four carriers, three battleships, ten cruisers, and numerous other warships and aircraft. The Battle of Leyte Gulf effectively ended Japan’s ability to conduct large-scale naval operations.
1945: The End of the War
Yalta: The Big Three, February 1945
As the war in Europe neared its end, the leaders of the three major Allied powers – Winston Churchill (Great Britain), Franklin D. Roosevelt (USA), and Joseph Stalin (Soviet Union) – met at Yalta in Crimea in February 1945. This conference, known as the Yalta Conference, aimed to coordinate final war strategy and plan for the postwar world.
At Yalta, the “Big Three” agreed on the postwar division of Germany, the prosecution of war criminals, and the formation of the United Nations. Stalin also pledged to enter the war against Japan after Germany’s defeat. However, disagreements remained, particularly regarding the future of Eastern Europe, foreshadowing the emerging Cold War tensions.
The bombing of Dresden, 13/14 February 1945
During the Yalta Conference, Allied leaders discussed and authorized the bombing of Dresden, a city hitherto largely untouched by Allied bombing. The bombing of Dresden on February 13-14, 1945, by British and American bombers, was intended to disrupt German communications and demoralize the German population as the Red Army advanced.
The bombing caused a firestorm that devastated Dresden, destroying 1,600 acres of the city. Estimates of the death toll vary widely, but most historians now estimate around 25,000 to 35,000 fatalities. The bombing of Dresden remains highly controversial due to the scale of destruction, the high civilian death toll, and its timing so late in the war.
The liberation of Bergen-Belsen, 17 April 1945
As Allied forces advanced into Germany, they began to uncover the horrors of the Nazi concentration camps. Bergen-Belsen concentration camp was liberated by British forces on April 15, 1945. The horrific conditions and piles of corpses shocked the world, bringing the full reality of the Holocaust to light.
The liberation of Bergen-Belsen and other camps exposed the systematic extermination of Jews and other persecuted groups by the Nazi regime. It is estimated that nearly six million Jews were murdered in the Holocaust, along with millions of other victims of Nazi racial policies.
VE Day, 8 May 1945
With Soviet forces closing in on Berlin from the east and Western Allies advancing from the west, the end of the war in Europe was imminent. Adolf Hitler committed suicide in his bunker in Berlin on April 30, 1945. Germany unconditionally surrendered to the Allies on May 7, 1945. Victory in Europe Day (VE Day) was officially proclaimed on May 8, 1945.
While VE Day marked the end of World War II in Europe after nearly six years of conflict, the war against Japan in the Pacific continued.
Nagasaki, 9 August 1945
To force Japan’s surrender and avoid a costly invasion of the Japanese home islands, the United States made the momentous decision to use atomic weapons. Following the successful testing of the atomic bomb in July 1945, the first atomic bomb, “Little Boy,” was dropped on Hiroshima on August 6, 1945. An estimated 78,000 people were killed instantly, and tens of thousands more would die later from radiation exposure.
Despite the horrific devastation of Hiroshima, Japan did not immediately surrender. Three days later, on August 9, 1945, a second atomic bomb, “Fat Man,” was dropped on Nagasaki, causing similar widespread destruction and death.
Japan surrenders, 2 September 1945
The atomic bombings, coupled with the Soviet Union’s declaration of war and invasion of Manchuria, finally compelled Japan to accept Allied surrender terms. Japan announced its surrender on August 15, 1945, commemorated as Victory over Japan Day (V-J Day).
The formal surrender documents were signed on September 2, 1945, aboard the USS Missouri in Tokyo Bay. This date, September 2, 1945, marks the official end of World War II, six years and one day after Germany invaded Poland.
Conclusion: The Six-Year Span of a World-Changing Conflict
So, how long was World War 2? From the commonly accepted start date of September 1, 1939, to the final surrender of Japan on September 2, 1945, World War II lasted for six years and one day. However, considering the earlier start of the Second Sino-Japanese War in 1937, the global conflict spanned approximately eight years if we include the Asian theater’s commencement.
Regardless of the precise start date, World War II was a protracted and devastating global conflict that fundamentally altered the political, social, and technological landscape of the world. Understanding its timeline and key events is crucial to comprehending its profound impact on the 20th century and the world we live in today.
