11 January 1942
“At 1841, while patrolling 270 miles NE of Johnston Island, I-6 sights a destroyer and crash-dives. Soon thereafter, a LEXINGTON-class carrier, one heavy cruiser and another destroyer appear on a southeasterly course at 19N, 165W. The carrier is USS SARATOGA (CV-3) of TF 14 under Rear Admiral Herbert F. Leary, steaming at 15 knots to rendezvous with USS ENTERPRISE (CV-6).
“Lt. Cdr. Inaba fires three Type 89 torpedoes in three-second intervals from 4,700 yards. At 1915, one hits SARATOGA starboard amidships, flooding three of her boiler rooms and killing six firemen. The carrier heels first to starboard, then to port, taking on 1,100 tons of water and losing headway. Seven minutes after the hit the escorting destroyers commence a counterattack, but fail to locate the submarine, escaping at 330-feet depth.
“The soundman of I-6 reports two loud explosions, followed by a series of smaller detonations, interpreted as breaking-up noises. After 2200, Lt. Cdr. Inaba reports two hits on a LEXINGTON-class carrier, claiming her as probably sunk.”