 Submarine Division 6 was subsequently reassigned to the IJN 3rd Fleet at the time of the attack on Pearl Harbor.Following the start of the Pacific War, "Chōgei" was based at Davao in the Philippines and was assigned a patrol area stretching to the Celebes, and south to the Flores Sea and Torres Straits.She was based at Staring-baai in February 1942 and was recalled to Japan in March.