National Liberation Front, 10 Years National Liberation Front, December 20th, 1970, Michel Nr. NLF 31-34; Four stamps with nominals of 20xu, 30xu, 50xu and 3 Dong (In NLF currency) were issued in perforation 11.0. The stamps were produced by the Tien Bo Printing House in sheets of 50 stamps each.
Mint blocks of six of the 30xu and 50xu value.
Here is the cancelled to order set.
These stamps were not officially released imperforate but a very small number of imperforate trial proofs have come to market. Here is the entire imperforate set in mint blocks of four.
Since these stamps were never used there is no genuine postal history. Sometimes one can see letters that were favor cancelled after the end of the war or NLF stamps mixed in with North Vietnamese stamps also used after the war but they are basically philatelic documents that were simply made up to please collectors. NLF stamps were not permitted to be used in the North until the currency harmonization in April of 1976 (mostly because the currency units were simply not compatible) so the mixed frankings one sees once in a while simply slipped through unrecognized or were obtained by bribing the postal clerk.
Here is such a philatelically inspired letter. It features the entire set with a nominal of 4 NLF Dong. The NLF Dong was devalued in April of 1976 by 500:1 which meant that at the time of mailing was only worth 0.008 North Dong. The standard letter rate in 1972 in the North was 0.12D or 0.06D for letters mailed intra-city, so clearly, this postage would have been rather insufficient. The envelope was either favor cancelled illegally in June of 1972 in Hanoi (at that time NLF stamps were not allowed to be used in the North due to the incompatible currencies) or favor cancelled with a back-dated cancel in Hanoi after the war.
Registration Nr. 200011