On Wednesday the United States marks the 70th anniversary of the Japanese attack on Pearl Harbor, the “Day of Infamy” that catapulted the country into World War Two.

Memorial events marking the December 7,1941 attack are being held throughout the country, the largest being on the Pacific island of Oahu, Hawaii, where the attack took place.

A dwindling number of Pearl Harbor survivors and World War Two veterans are among the 3,000 attendees expected at the event overlooking the USS Arizona Memorial, where the submerged remains of the fallen battleship rest. A moment of silence will be held at 7:55 in the morning , the exact moment Japan's Imperial Navy began the surprise attack.

In Washington, a wreath-laying ceremony is being held at the World War Two Memorial on the National Mall.

In a statement marking the day, U.S. President Barack Obama paid tribute to those whose died, saying that “their tenacity helped define the greatest generation.”

The attack by the Japanese on the U.S. naval base at Pearl Harbor was unprovoked. Four U.S. battleships sank or capsized, several hundred warplanes were destroyed and more than 2,400 service men, women and civilians died. It was the most devastating foreign attack on U.S. soil until September 11, 2001.

Many Americans draw a comparison between the attack on Pearl Harbor and the attacks on September 11, 2001. A spokesman for the Pearl Harbor Navy Yard says the comparison keeps the memory of Pearl Harbor alive for a new generation.

The U.S. declared war on Japan the day after Pearl Harbor was attacked. On December 11, 1941, Japan's Axis partners Germany and Italy declared war on the U.S., marking the nation's entry into the global conflict.