The Battle of Ewa Plain began just before 8 AM on December 7, 1941 and was part of the larger surprise attack by the Imperial Japanese Navy (IJN) on the United States of America military base at Pearl Harbor and other installations on the island of Oahu, and other islands considered defensive positions within the Territory of Hawaii. Based on current knowledge of the battle, it appears that Ewa Field was attacked approximately two minutes before Pearl Harbor. The last of the Japanese threats from this campaign ended on December 31, 1941, when Japanese submarine forces ceased attacks in Hawaiian waters after a final bombardment on December 31 and then withdrew their boats and support craft back to Mainland Japan to regroup and resupply for the next phase of battle. The Ewa Plain Battlefield is located in the southwestern corner of Oahu, Honolulu County, in a geographic area referred to as Ewa Plain, approximately 5.5 miles southwest of Ford Island (middle of Pearl Harbor). While the Battle of Ewa Plain encompasses three main population centers: Ewa Field, Ewa Villages, and Ewa Beach, only Ewa Field retains sufficient architectural, archeological, and/or landscape integrity to convey its historical significance. This includes retaining its integrity of location, setting, design, and association.