The attack on Pearl Harbor pulled the United States into World War II. On December 7, 1941, the surprise bombing by Japanese forces hit a major U.S. naval base in Oahu, Hawaii and killed 2,403 Americans. For millions of American families huddled around their radios, it was an unforgettable day marking the beginning of their World War II stories.

The U.S. declared war on Japan the next day, and men and women across the country rushed to join the war effort. All told about 8.3 million men and women enlisted in the U.S. Army during World War II, and millions more joined the war efforts on the homefront.

What Led to the Attack on Pearl Harbor?

The bombing of Pearl Harbor itself was a surprise, but the U.S. and Japan had been moving toward war for years. In the 1930s, the U.S. was on friendly terms with China and opposed Japan's growing militarism in Asia. And after the destruction of the Chinese capital of Nanking in 1937 by the Japanese and what became known as the Nanking Massacre, American popular opinion definitively favored China.

Tensions escalated on the political front as well. The U.S. tightened restrictions against Japan, cutting off shipments of petroleum and military supplies, as it increased aid to China. Instead of curbing Japanese expansion, as the U.S. hoped, it stoked anger and resentment.

In 1940, Japan aligned itself with Germany and Italy. Desperate for resources, Japan aimed to conquer new territory in Southeast Asia. The U.S. Navy's Pacific Fleet was the only thing standing in its way.

The U.S. did not expect an attack in Hawaii, 4,000 miles from Japan. It also did not think Japan had the firepower to inflict so much damage. Though Pearl Harbor was the base of the Pacific Fleet, it was not well defended. This played a large role in why Pearl Harbor was attacked. The fact that the bombing was a surprise made it especially powerful.

A Fateful Day for the USS Arizona

At 7:55 a.m. on Sunday, December 7, 1941, Japanese bomber planes appeared over Pearl Harbor. At 8:10, they dropped a 1,760-pound bomb on the USS Arizona, causing an explosion that reportedly lifted the battleship out of the water. They went on to hit seven other active battleships—the USS Oklahoma, USS Nevada, USS Pennsylvania, USS West Virginia, USS Maryland, USS Tennessee, and USS California—as well as a former battleship, the USS Utah, which had become a target ship.

In less than two hours, 353 Japanese aircraft destroyed or damaged 19 Navy ships. The attack killed 2,335 service members and 68 civilians, and wounded 1,178 people.

President Franklin Delano Roosevelt called the day Pearl Harbor was bombed one "which will live in infamy." After staying out of the war for two years, the U.S. was now forced into the global conflict. The attack unified public sentiment and made Americans, previously isolationist, ready to fight.

Pearl Harbor Remembrance Day

Americans will never forget the events of December 7, 1941. The pivotal date at Pearl Harbor is now designated as National Pearl Harbor Remembrance Day. Each year, veterans, family members, and visitors gather at the Pearl Harbor National Memorial to honor those lost in the attack. The site includes the USS Arizona Memorial, which was built on pilings above the sunken ship. It is the final resting place of over 900 sailors whose bodies were never recovered.

Finding Your Connection to Pearl Harbor

Sixteen million Americans, including the millions who enlisted as well as those who were drafted, went on to fight in World War II after the Pearl Harbor attack. And Ancestry can help you find your connection to these historic events. It has a vast database of records which you can explore for record collections covering the years around World War II (1939 – 1946). For instance you can look in the free-to-access 1940 U.S. Census to get a snapshot of your family just before Pearl Harbor, learning details like family member names, ages, and locations. Young men in your family who appeared in the 1940 Census might have soon been serving in the war or at least registering for the draft.

You can also search for draft cards: All 36 million of the available World War II young men’s draft cards are now available on Ancestry, after a multi-year project with the U.S. National Archives & Records Administration. They are particularly useful and interesting for family history because they include details like where the registrant lived, who they worked for, who their next of kin was—and even an idea of what they looked like, as draft cards had a physical description.

Curious to learn more about World War II and your family connection to it? Find and honor your ancestors who served in World War II.