On the 23rd February the mainland of the United States came under direct attack for the first time in the war. A Japanese submarine briefly surfaced and lobbed around thirteen shells onto the Oil Refinery at Ellwood, Santa Barbara on the Californian coast. Little damage was done as none of the shells hit any vital part of the installation.
During the night of 24/25 February 1942, unidentified objects caused a succession of alerts in southern California. On the 24th, a warning issued by naval intelligence indicated that an attack could be expected within the next ten hours. That evening a large number of flares and blinking lights were reported from the vicinity of defense plants. An alert called at 1918 [7:18 p.m., Pacific time] was lifted at 2223, and the tension temporarily relaxed.