As every festivalgoer knows, deep mud can make movement difficult, if not impossible. During the Vietnam war the US military weaponised this effect in an attempt to halt traffic on the strategically vital Ho Chi Minh trail.
Under the catchy name of Commando Lava, the top-secret project had Hercules transport aircraft flying at low level to disperse powder engineered to turn mud into glutinous super-mud.
The powder, composed of two chemicals commonly used in cleaning products, made mud more liquid so it could not support any weight. Vehicles would sink to their axles and get bogged down. The powder also slowed evaporation, so the mud lasted longer.
Planners believed Commando Lava would close the trail more efficiently than bombs, and would prevent vehicles using the trail for the entire rainy season if not longer. It would also not cause collateral damage or leave unexploded bombs. The unit carrying out the operation adopted the slogan: “Make mud, not war.”
An initial field trial in 1967 appeared to go well, but further drops had little effect. Aerial reconnaissance showed the Vietnamese were covering the affected areas with gravel. Traffic may have been slowed but continued as before.
Like determined music fans, the Vietnamese kept going despite the mud.