Early in the conflict, the Viet Minh's sabotage attempts failed to seriously damage the French railways, and most trains circulated without much protection. Beginning in 1947, however, the Viet Minh began to use mines, with circulation slowing to a crawl as they became more and more powerful.  In response, the French began using the armed armoured train La Rafale as both a cargo-carrier and a mobile surveillance unit.   In February 1951 the first Rafale was in service on the Saigon-Nha Trang section of the North–South line,   manned by the 2nd Foreign Infantry Regiment ( French Foreign Legion ). Use of the Rafale failed to deter the Viet Minh, however, who continued sabotaging the line, making off with its rails under cover of night and using them to create a 300-kilometre (190 mi)-long clandestine rail network between Ninh Hoa and Da Nang, in a Viet Minh-controlled area.  In 1954, following the signature of the Geneva Accords and the end of the First Indochina War, Vietnam—along with its railway system—was divided along the Bến Hải River in Quảng Trị Province .   
Sorry to hear about that. I also had an issue with my application when I mailed it because there was no mention of the $10 processing fee. Unfortunately the Vietnamese govt doesn’t seem to care to clearly spell out their policies or update them whenever they change. If I were traveling to Vietnam in less than a month’s time…I would definitely not apply for something like a Visa Exemption which requires you to mail in your passport. You can never be sure anything will get done in time…whether it is the VN government or the .