 The 17th Bombardment Group was moved to the new airfield from March Field, California and was equipped with the Douglas B-18 Bolo medium bomber.Following the Japanese attack on Pearl Harbor on 7 December 1941, the 17th Bombardment Group flew anti-submarine patrols off the West Coast of the United States with the new North American B-25 Mitchell medium bomber.As the first unit to operate the B-25, the 17th achieved another "first" on 24 December 1941 when one of its Mitchells dropped four 300-pound bombs on a Japanese submarine near the mouth of the Columbia River.