What is "v-mail"

V-mail, short for Victory Mail, was a hybrid mail process used during the Second World War in America as the primary and secure method to correspond with soldiers stationed abroad. To reduce the cost of transferring an original letter through the military postal system, a V-mail letter would be censored, copied to film, and printed back to paper upon arrival at its destination. The V-mail process is based on the earlier British Airgraph process.