Pearl Harbor was a lagoon and harbor on the Hawaiian island of O'ahu, in the Pacific Ocean on Earth.
During the 20th century, it served as a base for the United States Navy. The base was the site of a devastating attack by Japan in 1941, which was directly responsible for the entry of the United States of America into World War II. (VOY: "The 37's")
The movie From Here to Eternity, starring actor Burt Lancaster, depicted the events of this attack. Benny Russell encountered a newspaper vendor who preferred these war stories to science fiction. (DS9: "Far Beyond the Stars")
The attack would still be regarded more than four centuries later as the "stage for a bloody preamble to war," comparable to the attack on Station Salem-One. (TNG: "The Enemy")