Before World War II, the US was a Pacific power

Decades before Pearl Harbor, the US held major Pacific territories—Hawaii, the Philippines, Guam, American Samoa, and numerous island bases—giving it strategic reach across the western Pacific. This presence increasingly overlapped with Japan’s imperial ambitions in the region, contributing to rising tensions.

The US asked Japan to leave China less than two weeks before Pearl Harbor

On Nov. 26, 1941, Secretary of State Cordell Hull issued a note calling on Japan to withdraw from China and Indochina—terms Tokyo saw as impossible. The note confirmed to Japanese leaders that diplomacy had collapsed, accelerating plans for the Pearl Harbor strike (which had been formally approved Nov. 5).

Before Pearl Harbor, the US was a nonbelligerent ally to the Allied powers

Between September 1940 and December 7, 1941, the United States remained officially neutral—yet President Roosevelt incrementally shifted policy from “cash‑and‑carry” to Lend‑Lease, funneling critical military aid to Britain and other allies without entering the war.

Japan's imperial expansion in Asia in the 1930s set the stage for war with the US.

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Roosevelt’s post-Pearl Harbor address became one of America’s most iconic speeches

Delivered to a joint session of Congress on Dec. 8, 1941, President Franklin D. Roosevelt declared Dec. 7 “a date which will live in infamy.” The speech, heard by tens of millions of Americans, helped consolidate national support for entering the war.

Germany’s invasion of Poland in 1939 launched World War II

On September 1, 1939, Nazi Germany launched a surprise invasion of Poland using blitzkrieg—coordinated air bombardments and armored assaults—to overwhelm Polish defenses within weeks. This lightning-strike strategy shocked the world and signaled both the start of World War II and a revolutionary shift in modern military tactics.

The Pearl Harbor attack led to the mass internment of Japanese Americans

In the months after Pearl Harbor, the US forcibly removed and incarcerated about 120,000 Japanese Americans—two-thirds of them citizens. Driven by fear and racism, the policy is now recognized as a grave violation of civil rights.

The attack at Pearl Harbor required nearly a year of planning and preparation

In early 1941, Admiral Isoroku Yamamoto ordered detailed planning for a surprise carrier strike on Pearl Harbor. Japanese teams spent months refining torpedo modifications, training pilots, and rehearsing the complex attack.

How the US entered WWI in 1917

Originally taking a position of neutrality during the course of World War I, the United States of America eventually relented. Entering the war in 1917, support for the British and French had risen and Americans were incensed by Germany's overtures to Mexico and U-boat attacks that sank ships and ended American lives. See how and why the US entered WWI in this article.

See a visualization of the Japanese attack on Pearl Harbor.

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US intelligence failures contributed to the success of the Japanese attack

Despite breaking Japan’s diplomatic codes, US agencies failed to integrate warnings, successfully track Japan’s carriers, or even believe a Hawaii strike was possible (they also had not cracked Japan’s naval codes). Missed signals, ignored reports and poor coordination led to one of the worst intelligence failures in US history.

Should the US have entered into World War I?

America entered World War I in 1917, but had remained neutral until that point. President Woodrow Wilson addressed Congress, further underlining the USA's neutrality. Eleven weeks later, he asked for a declaration of war. With attacks by German saboteurs on an American munitions depot, it seemed he had no choice. But did he? This article asks what might have happened if the US stayed out of WWI.

Japan's attack on Pearl Harbor caused heavy losses but failed to cripple the US navy

Japan’s air assault sank or damaged 18 warships (including eight battleships) and destroyed 188 aircraft, killing 2,403 Americans, yet all three Pacific Fleet aircraft carriers were absent and survived, and vital infrastructure like oil depots and repair yards remained intact—preserving core US naval power and enabling a rapid recovery. Watch original reporting here.

Hitler's 1941 invasion of the USSR doomed Nazi Germany

Hitler unleashed Operation Barbarossa on June 22, 1941, underestimating Soviet resilience, Russian winter, and logistics. His overconfidence—rooted in early victories like France—turned this campaign into a strategic catastrophe, shifting the war’s momentum irreversibly—often cited as his greatest blunder.

Japan attacked Pearl Harbor largely because it was running out of oil

This video traces how US-led sanctions and Japan’s near-total dependence on imported oil pushed Japanese leaders toward a high-risk plan: seize Southeast Asian oil fields and neutralize the American Pacific Fleet, hoping Washington would negotiate rather than fight.

The attacks prompted a quick jump in American public support for war

In a Gallup poll taken days after the attack, an extraordinary 97% of Americans approved Congress declaring war on Japan—reflecting overwhelming national unity in the wake of the strike.

What happened to Americans who were in Japan during Pearl Harbor?

When Japan bombed Pearl Harbor in December 1941, roughly 10,000 American civilians were stranded in Japanese-occupied territory. Tense diplomatic negotiations eventually secured two prisoner exchanges conducted via ship across 20,000 nautical miles to return nearly 3,000 Allied civilians, while Japanese Americans in North and South America were sent in the opposite direction, many to a country they had never called home.

The US Pacific strategy sought control of key islands to close in on Japan

The US adopted a two-pronged "island hopping" campaign across the Central and Southwest Pacific from 1943–44, deliberately targeting strategically crucial but less-defended islands. This allowed forces to bypass heavily fortified Japanese strongholds and build airfields for bombers aimed at Japan, drastically accelerating the path toward Tokyo while conserving manpower and resources.

The Pearl Harbor attack was influenced by a British raid on Italian battleships

Japan closely studied Britain’s 1940 attack at Taranto, where carrier-launched torpedo planes crippled Italian battleships in shallow water. Although Japanese planning for Pearl Harbor was already underway, Taranto demonstrated the plan’s feasibility and strengthened Japanese confidence that a surprise carrier assault could cripple the US Pacific Fleet.

See how newspapers broke the news of the attack around the world

This collection showcases front pages from cities around the globe reacting to Pearl Harbor in real-time—capturing the shock, fear and uncertainty as the US entered World War II.

Why Captain America sparked outrage in 1940

In 1940, Captain America’s debut showed him punching Hitler months before the US entered WWII. The bold cover sparked backlash and even threats.

Congress has formally declared war 11 times across five conflicts, the last in 1942

The five declared wars were the War of 1812, the Mexican-American War, the Spanish-American War, World War I, and World War II. Every major American military conflict since Korea, Vietnam, Iraq, and Afghanistan has been fought without a formal declaration.

Japan had the world's best carrier aviation in 1941

In late 1941, Japan possessed the world’s most powerful carrier fleet and the best-trained naval aviators, giving it a short-term edge over the US. But Japan couldn’t replace ships or pilots quickly, and US industry would soon outbuild it.

A single bomb on the USS Arizona killed 1,177 crew members in seconds

When a Japanese armor-piercing bomb triggered the explosion of the USS Arizona’s forward magazine during the attack, the blast killed 1,177 crew members within moments—accounting for nearly half of all American deaths at Pearl Harbor.

Franklin D. Roosevelt's 1941 speech framed World War II as a global fight for universal rights

Eleven months before the attack on Pearl Harbor, President Roosevelt outlined four fundamental freedoms that, in his words, people "everywhere in the world" ought to enjoy—speech, worship, freedom from want, and freedom from fear.

The perplexing Battle of Los Angeles in 1942 generated swaths of UFO conspiracies

On Feb. 24-25, 1942, weeks after the Pearl Harbor attack, a US military radar warned of enemy aircraft. A citywide blackout went into effect, powerful searchlights were lit up, and US forces fired artillery at what they believed to be the enemy. However, no confirmed enemy planes were ever identified. Eyewitnesses reported seeing large objects flying overhead, and much of the public speculated about UFOs and extraterrestrial attacks.

Wartime conferences exposed cracks in the US–Soviet alliance

At the Tehran, Yalta and Potsdam Conferences, Allied leaders coordinated WWII strategy—but deep disagreements over postwar Europe foreshadowed the Cold War. The USSR’s push for influence in Eastern Europe clashed with US and British calls for self-determination.

When German submarines lurked in US coastal waters

During World War II, German submarines (also known as U-boats) prowled the Southern coast of the US in 1942 and 1943, sinking more than 60 ships and killing 600 Allied soldiers. The campaign is less well-known, since the major battles in Stalingrad and Midway happened at the time. Several of these submarines and the ships they sank are now popular diving spots.

The “Phoney War” was an eight‑month build-up to war

From September 1939 to May 1940, following their war declaration on Germany, Britain and France entered a phase of military inaction—even as civil defence measures, naval blockades, and rationing intensified at home. Skirmishes were limited, but the decisive fighting didn't begin until Germany invaded Norway and France in April–May 1940, abruptly ending the uneasy stalemate.

How the Great Depression and end of WWI paved the way for Hitler's rise to power

The end of WWI was triggered by an armistice that blamed the conflict on Germany and required the financially struggling country to pay reparations. This outraged nationalists and ignited conspiracies that Hitler was able to capitalize on, according to this six-minute video. It was during this financial strain that the Great Depression hit.

World War II's Battle of Savo Island was the worst wartime naval defeat in US history

On Aug. 9, 1942, a larger, radar-equipped Allied fleet lost four heavy cruisers off Guadalcanal in the Pacific theater without sinking a single Japanese ship. The Navy kept the humiliating rout secret from the public for years. Experts argued failure resulted from fractured command, not inferior arms or ships.

How two US Presidents defined WWII and its aftermath

The National WWII Museum’s “To the Best of My Ability” podcast series delves into how Presidents Franklin D. Roosevelt and Harry S. Truman steered the US through World War Two.

The Battle of Midway flipped the balance of power in Pacific naval dominance

Between June 4–7, 1942, U.S. carrier-based aircraft, aided by broken Japanese codes and radar detection, ambushed and sank all four Japanese fleet carriers while losing only one, decisively undermining Japan's offensive capacity and marking the turning point in the Pacific War.

FDR stayed composed as he absorbed the news of Pearl Harbor

This video reconstructs Roosevelt’s steady, methodical response on Dec. 7, 1941, from his first briefing to drafting his speech to Congress. It demonstrates how FDR maintained composure and moved rapidly to prepare the nation for war.

How much did WWII cost?

Though it lasted fewer than four years, World War II was the most expensive war in United States history, according to this infographic. Read through it to see how much WWII cost and learn about the consequences of financing such an expensive conflict.

Okinawa’s ferocity convinced the US atomic bombs was necessary

The brutal 82-day Battle of Okinawa—where US forces suffered nearly 50,000 casualties and Japanese military and civilians lost over 200,000 lives—clinched the grim reality that a full invasion of Japan would be even bloodier. This stark lesson directly shaped American decisions to deploy atomic weapons, aiming to avoid a potentially catastrophic ground war on the Japanese mainland.

Hawaii lived under martial law for nearly three years after Pearl Harbor

After the attack, Hawaii was placed under sweeping military rule—curfews, censorship, warrantless arrests, ID papers, and mass detentions transformed everyday life. More than 2,000 people were arrested within 48 hours of the attack, and the islands remained under martial law for nearly three years.

European leaders pursued appeasement of Hitler in the 1930s, hoping to avoid war.

The 1915 sinking of the Lusitania precipitated World War I

In 1915, the British RMS Lusitania sank after being torpedoed by a German submarine. The Germans claimed the ocean liner was transporting munitions. Almost 1,200 civilians were killed in the disaster, which became a symbol of German aggression in the lead-up to World War I.