2x Navy Cover Cachet & Launch Invitation: US Grayling Submarine, September 1940 Portsmouth
Launch is stated at September 4th but this is postmarked a bit later (post-mark reads September 16).
Good condition as shown, includes all three pieces shown: addressed, stamped, and cancelled cover, original event invitation, and an addressed but unstamped/cancelled cover. Some staining from adhesives as shown as well as a few other spots of soiling present.
This is part of a small collection from a relative who worked as a civilian engineer in the Portsmouth shipyard for many years; there are other ship & submarine first day covers available in separate postings (some with invitations to launch events) - please let me know if you are interested in a combined purchase.