Universal Postal Union regulations have for many years allowed that mail posted ON THE HIGH SEAS, and bearing stamps of the same country whose flag the vessel flies, might be put ashore at the first port of call, where it is postmarked with the paquebot marking of that port and sent on its way to the addressee. The Republic of Korea, however, had not utilized paquebot mail until it was introduced there in late 1951 by Captain Charles E. Milbury, who is noted for his famous “Sea-Jug Post”.
I have been fortunate in acquiring examples of all the various types of Korean paquebot markings known to date. The first paquebot mail was sent from Pusan, Korea on December 25, 1951, and this mail was stamped with a special rubber stamp supplied by Capt. Milbury at his own expense. These first covers were questioned as to their authenticity by several writers in the philatelic press. This matter was cleared up by a letter from Rew, Wan Sik, an official of the Ministry of Communications, Republic of Korea, in which he stated that these covers of December 25, 1951 were the first accepted as paquebot mail by the Republic of Korea. I have never seen figures as to the number of covers posted on that date except reference to the ‘fact that the number was small.

The Sea-Jug-Post was invented by Captain Charles E. Milbury from the MV Arizona Sword in September 1949. Who knows about the “E.” in his first name (“Ellis?”) and who knows about his dates of birth and death?
A Sea-Jug-Post stamp on covers (from 1950 and 1951) from the MV Arizona Sword was seen on the philatelic market with the name “Neptune”, but also covers bearing this stamp and the additional (post)mark “Kingdom of Neptune”. A special curiosity is the fact that a postmark showing the words “Merry Christmas from the Kingdom of Neptune” is also known on Sea-Jug-Post covers from the M. V. Oregon Sword from December 1954, although no Neptune stamp was used on these covers. Any detailed information to the use of this Neptune stamp and its Kingdom is welcome.