The Japanese submarine screen was not ideally configured to attack a fleet sortie because its boats carried midget submarines rather than operating solely as free-hunting attack boats. On 6 December they were still moving into their final positions for a launch scheduled around 0100 on the seventh. An American morning departure could therefore pass before the screen was fully established. Even a boat that sighted the sortie might avoid attacking in order to preserve stealth and the timed harbor mission. The episode illustrates how mission focus can suppress initiative: commanders might not even report an unexpected movement promptly if they judged the assigned midget-submarine launch to be paramount.
Notable Point · 39:09-40:28
Why Japanese submarines might not stop the sortie
The Japanese submarines were moving into position and focused on launching midget submarines, leaving a 6 December American departure a chance to pass unnoticed.