Indochina, Marshall Plan, 1941, Michel Nr. IND 254-255; Two stamps with nominals of 10C and 25C were issued in France but the stamps did not reach Indochina due to disruption of transportation. As a result very few of these stamps were postally used. Some of them were physically brought by travelers to Indochina during or after the war and then used there. All used stamps or postally used letters are pretty rare.
Here is the used 10C stamp.
Very rare registered letter featuring the Marshall Plan set together with the 25C Domestic Scenes II stamp paying an overall postage of 60C on a domestic registered letter that the well known philatelist Jacques Dessrousseaux mailed to himself in Saigon. Saigon arrival cancel a day later on the reverse.
Registration Nr. 090300