Civil Censorship Study Group

Applied before leaving Honolulu? (unlikely)
Applied when returned from USA to Honolulu (when cover arrived)?
Applied after being held in Honolulu for a period of time?

I am familiar with the CCSG articles on the topic (1995 and 2011), but would like some clarification when the marking would likely be used.

Cover posted in Honolulu December 6, 1941, (prior to attack on Pearl Harbor), destined for Hong Kong, China. Sent by surface mail, the cover eventually reached San Francisco. By that time the attack on Pearl Harbor had occurred and also the attack on Hong Kong. Consequently, the cover could not proceed to Hong Kong.

The RTS marking was applied in San Francisco, then returned to Honolulu (July 10, 1942) and subsequently “Released” by the I.C.B. (# 49), and returned to the sender. Was the cover “held” in SF – then returned later to Hawaii in July? Is July 10, 1942 the actual date the ICB marking was used?

I agree that this cover would have been on a boat bound for HK when Pearl Harbor was attacked. So it would not have been in Hawaii when censorship began a week later. My understanding is that ships at sea were supposed to make for the nearest (safe) US or Canadian port after that. Given what had just happened at Honolulu, I doubt that would have been viewed as a viable safe port. I also agree that the RTS marking is from SF, so it seems logical that the ship eventually made it back to SF where the mail was off-loaded.

Logic says that this cover did pass through the SF censor's office, as that is what international mail arriving in SF was supposed to do. They could have checked it against the watch list and decided not to open it, without leaving any markings. They could also have decided to hold (condemn) it for a period of time and quietly release it later, again without marking it. (Standing orders were to return surface mail to the post office within 96 hours after receiving it, absent exigent circumstances.) For what it's worth (which may be nothing), I seem to recall seeing the same several-months delay on mail to Europe returned to sender after passing through the NY censorship station. Whether there was a formal order to release the pre-war returned mail after 6 months or so would seem likely, but the smoking gun, if it exists, is still waiting to be found in the Office of Censorship records in the National Archives.

That the cover would have been sent unopened from SF to Honolulu for examination seems logical, on the theory that a local examiner might pick up nuances that would have been missed by someone in SF. The censorship office in Honolulu would have been under those same sanding orders to return this cover to the mails within 96 hours after receiving it. And since applying the Released by ICB marking would have come at the end of the process, it is safe to assume that it was applied on the date of the Honolulu backstamp (or the day before at the earliest).