I served with 5RAR as Pioneer Platoon Commander for the year I was in Vietnam in 1969. I wrote a book, Call Sign Tiger 62. The tasks of the Pioneer Platoon included all forms of demolition, dealing with mines and booby traps, flamethrower support, construction and destruction of anything anyone could think of, tunnel clearance and any other task that couldn’t be done by anybody else. After finishing these tasks each pioneer would then perform all the duties of a normal infantry soldier. The tunnels were challenging. What were you feeling around for in tunnels? Snakes! We had a pistol and you just went in and searched it for mines or explosives or anything else there.