US Navy Censored cover from Upham Naval Air Station, 1942
The Isthmus of Panama has had a US military presence since 1850 when US Marines were sent to safeguard the Panama Railroad Company’s efforts to build a coast-to-coast railroad across the isthmus (no small task despite the diminutive distance between coasts).
During World War II, the US Naval Submarine Base named Coco Solo was turned into a US Naval Air Station. Perhaps because of the somewhat whimsical name of the base (meaning “Lonely Coconut”) it was renamed Upham. Upham served as the base of operations for a squadron of P38 Lighting aircraft for defense of the Panama Canal. The Panama Canal was seen as a strategic resource during World War II because it offered the ability to move resources from one ocean (and one front) to the other with relative ease.
There were only two types of hand cancel devices used that featured the base name of Upham. This one was used from December 1, 1939 to September 15, 1942*. What I find particularly striking about this cover is that the censor marking was made with a bright blue ink. The majority of censor markings I have seen from Upham were made with black ink.
* The Postal Markings of the Canal Zone, 2nd Ed. by Lawson Entwistle, Canal Zone Study Group, 1992
Canal Zone Postal History 