Following the Japanese attack on Pearl Harbor on , 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 bombs on a Japanese submarine near the mouth of the Columbia River. The 17th Bomb Group was reassigned in February 1942 to Columbia Army Air Base in South Carolina, where crews from the group were selected to carry out the Doolittle Raid on Japan in April.