Timeline of World War II – Key Events in Order

World War II was a truly global conflict that engulfed the world from 1939 to 1945. With Nazi Germany’s invasion of Poland on September 1, 1939, Britain and France declared war two days later. Over the next six years, the two opposing coalitions – the Allies (including the UK, USSR, USA, China, and others) and the Axis (led by Germany, Italy, and Japan) – fought fierce campaigns on multiple continents. Tens of millions perished; as one historian notes, by war’s end about 20 million military personnel and 40 million civilians were dead. (Estimates range even higher – up to 70–85 million total killed.) The war reshaped global politics: it led to creation of the United Nations, decolonization of Asia and Africa, and the emergence of the US and USSR as superpowers.

Before 1939, the stage was set by aggressive expansion of dictatorships. In Asia, Japan had invaded Manchuria in 1931 and waged full-scale war on China beginning July 1937. In Europe, Italy conquered Ethiopia (1935–36), and Germany annexed Austria (the 1938 Anschluss) and the Sudetenland (via the Munich Agreement). These actions, along with the Spanish Civil War and militarization of Japan, foreshadowed a larger world war. By 1939, two massive militaries clashed in Asia and tensions exploded in Europe – setting the scene for worldwide conflict.

Key Timeline Summary (1939–1945):

• 1939: Germany invades Poland on Sept 1; Britain & France declare war; USSR invades eastern Poland; Winter War with Finland begins.

• 1940: Germany overruns Scandinavia (Denmark/Norway) and Western Europe (Belgium, Netherlands, France); Italy enters war; Battle of Britain defends UK; Axis powers sign Tripartite Pact.

• 1941: Germany invades USSR (June 22); Japan attacks Pearl Harbor (Dec 7), dragging the US into the war; Japan quickly conquers much of Southeast Asia.

• 1942–1943: Turning-point battles shift momentum: Allies halt Axis advances in North Africa (El Alamein, Oct 1942) and in the Pacific (Midway, June 1942); Soviet victory at Stalingrad (Feb 1943) traps and defeats a German army; Allied forces land in North Africa (Operation Torch, Nov 1942) and Sicily (July 1943); Italy switches sides (Sept 1943).

• 1944: Allies open a second front in Western Europe with D-Day (Normandy landings, June 6); Soviet offensives (Operation Bagration, June 1944) drive back Germany; France is liberated; Romania and Bulgaria surrender; US and USSR push closer to Germany.

• 1945: Soviet troops encircle Berlin (April); Hitler commits suicide (April 30); Germany surrenders (May 7–8). In the Pacific, Allies capture Okinawa (spring 1945), then drop atomic bombs on Hiroshima and Nagasaki (Aug 6 and 9); the USSR declares war on Japan (Aug 8) and invades Manchuria; Japan surrenders (Sept 2).

Outbreak of War (1939)

In late 1939, what had been a series of local conflicts erupted into a world war. The Molotov–Ribbentrop Pact of Aug 23, 1939 secretly divided Eastern Europe between Germany and the USSR. Two days later, on September 1, 1939, Hitler’s army invaded Poland from the west. Britain and France responded on September 3 by declaring war on Germany. Poland was quickly defeated: German forces captured Warsaw by late September and partitioned the country with the Soviets. The Soviet Union also invaded eastern Poland on Sept 17, pushing Poland’s government into exile.

• Sept 1, 1939: German troops cross into Poland, firing the first shots of WWII.

• Sept 3, 1939: Britain and France declare war on Germany, honoring their guarantees to Poland.

• Sept 17, 1939: The Soviet Union invades eastern Poland, further dismembering the country.

• Winter 1939–40: The USSR attacks neutral Finland (the Winter War), ending in a costly Finnish defeat and some territorial loss for Finland.

By the end of 1939, war was underway in Europe, but the front lines had largely frozen into a quiet phase (“Phoney War”) in the west. Meanwhile in Asia, Japan continued its aggressive expansion. On July 7, 1937, long before Europe’s conflict, Japan had invaded China, initiating a brutal war that merged into WWII. This Sino-Japanese War (1937–1945) saw atrocities like the Nanjing Massacre and strained China’s society. Japan would occupy much of China and later Southeast Asia during the wider war (more on that below).

(For an image of the war’s outbreak, one might use a photograph of German tanks rolling into Poland. Alt text suggestion: “German Panzer tanks crossing the border into Poland on September 1, 1939.”)

Axis Expansion and Blitzkrieg (1940–1941)

After Poland’s defeat, Axis powers moved swiftly to conquer Europe. In spring 1940, Germany unleashed “Blitzkrieg” tactics to overwhelm Denmark and Norway. On April 9, 1940, Denmark fell in hours and Norway surrendered on June 9. At the same time, Germany’s armies struck west: on May 10, 1940 they invaded Belgium, the Netherlands, and Luxembourg, and within weeks overran France. British and Allied troops were forced to evacuate at Dunkirk (late May–early June 1940) and French resistance collapsed. By June 22, 1940, France had signed an armistice: northern France and much of the Atlantic coast came under German occupation, while a nominal Vichy regime governed the south.

• Apr–Jun 1940: Germany conquers Denmark and Norway. In May–June, German forces attack Belgium, the Netherlands and France; Paris falls on June 14; France signs armistice on June 22.

• Jun 10, 1940: Italy enters the war on Germany’s side. Mussolini’s Italy invades southern France (June 21) and attacks British positions in North Africa.

• Jul–Oct 1940: The Battle of Britain – Germany’s air force (Luftwaffe) bombs Britain in preparation for invasion. The RAF’s determined defense turns back the assault, marking Hitler’s first major setback.

With France defeated, the Axis dominated much of Europe. To cement their alliance, Germany, Italy, and Japan signed the Tripartite Pact on September 27, 1940, formally creating the Axis coalition. Several smaller nations joined them: Hungary, Romania, Slovakia, and later Bulgaria each allied with the Axis by early 1941. Italy, meanwhile, pursued its own conquests: from Italian bases in Albania, Mussolini’s forces invaded Greece in October 1940 (though Greek resistance ultimately required German aid in 1941).

In North Africa, Italian troops had attacked British Egypt in 1940. To assist their Axis partner, Germany dispatched the Afrika Korps under General Erwin Rommel in early 1941. Rommel’s forces pushed the British back into Egypt by mid-1941, threatening the Suez Canal. Africa thus became another major theatre.

Meanwhile, political alliances kept shifting: in April 1941, Germany and Italy (with Bulgarian support) invaded Yugoslavia and Greece, subduing the Balkans by June. The puppet Independent State of Croatia was established (Axis-aligned) in April 1941. These moves secured Germany’s southern flank in Europe and allowed it to redirect forces eastward.

Suggested image: A suitable illustration could be German tanks or infantry in France, 1940. Alt text: “German armored division advancing through the French countryside after the fall of France in 1940.”

The Global War Breaks Out (1941)

By 1941, World War II had truly become global. The next giant wave of Axis offensives came on two fronts:

• June 22, 1941 – Eastern Front (Operation Barbarossa): Hitler broke the Nazi-Soviet non-aggression pact and launched a massive invasion of the Soviet Union. Millions of German and Axis troops poured across the Polish and Baltic borders into Soviet territory. The assault was initially unstoppable: within weeks the Wehrmacht overran the Baltic states and laid siege to Leningrad. In the center, German forces pushed toward Moscow and captured Smolensk by August. In the south, they took Kiev (Kyiv) and were heading toward the oil fields of the Caucasus. Operation Barbarossa opened the Eastern Front – the largest and bloodiest front of the war. Although the Soviets were stunned by the attack, they launched fierce defenses and counterattacks, notably the Soviet counteroffensive at Moscow in December 1941 which would stall the German advance.

• December 7–8, 1941 – Pearl Harbor and Pacific War: Japan had long been at war in Asia. On December 7, 1941, Japanese aircraft attacked the US fleet at Pearl Harbor, Hawaii, devastating battleships in one morning. On December 8, the United States declared war on Japan, immediately entering World War II. Simultaneously, Japan carried out surprise assaults on British and American holdings across the Pacific and Southeast Asia. Within days Japanese troops had attacked the Philippines, Hong Kong, Singapore, and Malaya. By early 1942, Japan had overrun the Philippines, Indochina (Vietnam, Laos, Cambodia), Malaya, Singapore, and Burma. They also attacked US outposts like Guam and Wake Island. This swift Japanese advance threatened to cut off Australia and bring Southeast Asian oil and resources into the Axis camp.

In response, the US (and British) Pacific forces braced for a long fight. The simultaneous wars in Europe (Germany vs. USSR/Allies) and Asia (Japan vs. China/Allies) now merged into one global conflict. Indeed, as historian Mark Stille writes, Hitler’s invasion of Poland “launched” World War II on a worldwide scale.

(Image suggestion: Admiral Chester Nimitz looking at a map of the Pacific War. Alt text: “U.S. Navy Admiral Chester Nimitz studying a map during World War II Pacific campaign.”)

Turning Points (1942–1943)

By 1942 the Axis seemed poised at its zenith – German armies were deep in the USSR and Africa, and Japan held a vast Pacific empire. But this period saw pivotal battles that turned the tide in favor of the Allies on multiple fronts:

• Battle of Midway (June 1942): In the Pacific, the US Navy decisively defeated a major Japanese fleet. In early June 1942, just six months after Pearl Harbor, US aircraft carriers ambushed and sank four Japanese fleet carriers at Midway Atoll. Midway halted Japan’s advance across the Pacific and shifted naval air superiority to the Americans.

• North Africa – First Battle of El Alamein (Oct 1942): After months of see-saw fighting, British Commonwealth forces under General Bernard Montgomery stopped Rommel’s push into Egypt at El Alamein. The Allied victory in late October 1942 smashed Axis momentum in North Africa. The following month, in Operation Torch (Nov 8, 1942), US and British forces landed in French North Africa (Algeria and Morocco). The two fronts cornered German-Italian forces: by May 1943, all Axis troops in Tunisia surrendered, ending the North African campaign in Allied favor.

• Stalingrad (Aug 1942 – Feb 1943): On the Eastern Front, Germany launched a summer offensive aiming to capture Stalingrad on the Volga River. Fierce urban combat raged in Stalingrad through 1942. In November, the Soviets counterattacked, encircling Germany’s 6th Army in the city. Hitler forbade a retreat, and by February 2, 1943, the encircled German forces surrendered. The Battle of Stalingrad was a catastrophic defeat for Germany and a major Soviet victory, marking a turning point on the Eastern Front.

• Guadalcanal (Aug 1942 – Feb 1943): In the Pacific, the Allies launched their first major offensive against Japan by seizing Guadalcanal and nearby islands in the Solomon Islands. Over six months of brutal jungle warfare, US Marines repelled repeated Japanese counterattacks. By February 1943, the Allies controlled Guadalcanal, forcing Japan onto the defensive across the Pacific.

• Battle of the Atlantic (Throughout 1942–43): The ongoing Allied naval blockade of Germany in the Atlantic began to prevail. Although German U-boats wreaked havoc early on, Allied use of convoys, long-range aircraft, and radar began to turn the tide by 1943. (By mid-1943, the Battle of the Atlantic was safely in Allied hands.)

  List of other 1942–43 campaigns:

  • Kursk (July 1943): In the largest tank battle in history, the Soviets blunted Germany’s last major offensive in the USSR. After Kursk, the Red Army went mostly on the offensive for the rest of the war.

  • Sicily and Italy (July–September 1943): Allied forces invaded Sicily in July 1943 and then mainland Italy. Mussolini was deposed on July 25, 1943, and Italy surrendered on September 8. However, German troops quickly occupied northern Italy, and heavy fighting (Monte Cassino, Anzio) continued into 1944.

  • Eastern Europe: As the Soviets advanced westward after Stalingrad, they liberated Kiev (Nov 1943) and pushed into eastern Europe in 1944 (Bulgaria and Romania switched sides, September 1944).

By the end of 1943, Germany and Japan were mostly reacting to Allied operations. The momentum had shifted decisively. As one observer notes, “by 1942 the Allied Powers started to systematically bomb Germany… until Germany’s surrender in 1945”. Indeed, from late 1942 onward, Axis forces were increasingly on the defensive.

(Image suggestion: A WWII era map showing the global conflict in 1943, with fronts in Europe, North Africa, and the Pacific. Alt text: “Map of World War II theaters and fronts in mid-1943, showing Allied advances and Axis-held territories.”)

The Fall of the Axis (1944–1945)

In 1944, the Allies opened multiple fronts that would crush the Axis powers. The decisive blow in Europe was D-Day (June 6, 1944). On that day, over 150,000 American, British, and Canadian troops landed on the beaches of Normandy, France. By establishing a “Second Front” in Western Europe, the Allies unleashed a massive offensive. In the weeks following D-Day, they broke out of Normandy (July 1944), liberated Paris on August 25, and by autumn had driven into Belgium, the Netherlands, and Germany’s borders.

Meanwhile in the east, the Soviet Operation Bagration (June–August 1944) smashed German Army Group Centre in Belarus. The Red Army surged westward, liberating much of Soviet territory and moving into Eastern Europe. In August 1944 Romania switched sides and surrendered, and Bulgaria surrendered a few days later. The Germans evacuated Greece and the Balkans, facing the prospect of Allied armies on both sides of the Rhineland.

• June 6, 1944 (D-Day): Allied troops land at Normandy beaches. Within days the invasion is secure, forcing Germany to divert forces to France.

• July–August 1944: Allies break out of Normandy and liberate Paris; at the same time, Soviet offensives reclaim Belarus and Eastern Poland.

• August 15, 1944: Allies invade southern France (Provence) and drive toward the Rhine. Soon, most of France, Belgium, and parts of the Netherlands are liberated.

• Winter 1944: Germany launches a last gasp counterattack in the Ardennes (Battle of the Bulge, Dec 1944–Jan 1945), which fails and depletes German reserves.

In Italy, Allied forces finally broke through the Gothic Line in late 1944 and advanced into the Po Valley. Rome had fallen in June 1944, and fighting continued north until German forces withdrew in early 1945.

By early 1945, Germany was surrounded. Soviet troops launched their final offensive towards Berlin in April 1945, encircling the city by month’s end. As the Soviets closed in, Adolf Hitler committed suicide on April 30, 1945. Germany’s unconditional surrender followed almost immediately. On May 7, 1945, the German High Command signed surrender documents at Reims; the surrender took effect on May 8 (V-E Day). Fighting in Europe ceased, though minor actions continued until May 9 in the USSR (Soviets celebrate Victory Day on May 9).

In the Pacific, the Allies pressed home the offensive. Major amphibious assaults (e.g. at Iwo Jima in early 1945) and relentless island-hopping brought Allied forces within striking distance of Japan. The bloodiest Pacific battle, Okinawa, was won by the Allies in May–June 1945. By early summer 1945, Japan’s navy was shattered and its home islands were under threat.

Finally, on August 6 and 9, 1945, the United States dropped atomic bombs on Hiroshima and Nagasaki, respectively. These unprecedented bombings, combined with the Soviet Union’s declaration of war on Japan on August 8 and invasion of Manchuria, forced Japan to surrender. On September 2, 1945, aboard the USS Missouri, Japan signed the formal surrender document, officially ending World War II.

Suggested image: A photograph of the D-Day landings (Allied troops storming a Normandy beach). Alt text: “Allied soldiers wading through the surf onto Omaha Beach, Normandy, on D-Day, June 6, 1944.”

Aftermath and Global Impact

World War II was the most destructive conflict in history. It caused an estimated 70–85 million deaths worldwide and reshaped international affairs. In Europe, Nazi Germany was divided and occupied; war criminals were tried at Nuremberg. Empires of Britain, France, and others began to collapse as colonies in Asia and Africa pressed for independence – the war had weakened the old colonial powers. The Soviet Union and the United States emerged as rival superpowers, initiating the Cold War (with decades of tension and proxy wars). In 1945, world leaders founded the United Nations to prevent future wars and foster cooperation, with the wartime Allies (US, UK, USSR, China, France) as its Security Council’s permanent members.

In the United States and the Soviet Union, wartime economies shifted to peacetime growth, launching a prolonged era of economic expansion (and the U.S. baby boom). In Europe, recovery was slow until initiatives like the Marshall Plan helped rebuild infrastructure and industry. Socially and culturally, the war’s legacy was profound: it directly led to movements for civil rights, decolonization, and a re-examination of international law and human rights (spurred by revelations of the Holocaust and other atrocities).

Today’s world borders and institutions still reflect WWII’s outcomes. For example, Germany was partitioned until reunification in 1990, Japan adopted a pacifist constitution under U.S. occupation, and NATO was formed in 1949 as a collective defense against Soviet power. The global order of the late 20th century – from the European Union’s origins to U.S.-China relations – can be traced back to the power shifts and alliances forged in the war’s aftermath.

In summary, the World War II timeline (1939–1945) unfolded in clear chronological stages: war’s outbreak (1939), Axis conquests (1940–41), turning-point battles (1942–43), and final Allied offensives (1944–45), leading to Axis defeat. This comprehensive timeline highlights how the conflict engulfed Europe, Asia, Africa, and the Pacific, and how each turning point – from Stalingrad to Midway to D-Day – propelled the Allies to victory. The war’s legacy – massive human costs, geopolitical realignments, and a new commitment to international cooperation – continues to shape our world.

References: Credible historical sources were used to compile this timeline, including official war archives and scholarly overviews. For instance, the United States Holocaust Memorial Museum provides a detailed chronological list of WWII events, and History.com offers an accessible timeline of major battles and outcomes. These and other sources ensure accurate dates and context for the key events mentioned above.

• US Holocaust Memorial Museum – World War II: Key Dates and Timeline.

• HISTORY.com – “World War II Battles: Timeline” (American Experience).

• Wikipedia – “World War II” (overview, causes and consequences).

• Additional academic and historical references on WWII events (as cited in notes above).