The guide showing us how small it the entrance actually is
This fascinating pictures shows how small the actual entrance to the tunnels at Cu Ci were. During the height of the Vietnam War against the US, these tunnels were the main deciding factor in determining how the war swung from the stronger, larger built soldiers, superior forces of the US to much smaller, poorer armed both in technology and communications but motivationally and possibly strategically stronger Viet Cong army.
Placing the top of the tunnel covered with dead leaves
The guide shows us exactly how small the tunnel entrance is ; hence many of the enemy could not find the VC or after an ambush had taken place, the VC somehow had disappeared into thin air. In fact they went underground. A very brilliant maneuvre and tactic using only manpower and motivation to dig these long tunnels. Once the entrance is shut, it is pitch black and everyone inside is supposed to keep silent as their entire unit and lives depended on it. The US forces upon discovering the tunnels would first throw a couple of hand granades or smoke granades to kill, maim, or stun or even smoke out the VC. Once they came dashing out, they were easy prey or surrendered.
The entrance totally hidden from plain sight ; you need to practically walk over the entrance to notice it if you actually do.
The LURPs Long Underground Reconnaissance Patrols were the specialists Rangers tasked to flush out these tunnel combatants. Called the Tunnel Rats, they would sleep most of the day and only operate to full efficiency at night. Their jobs were ruthless and it was savage from what I read about how they carried out their jobs.
4 Levels underground - Tunnel Complex ; there are even small pipes to emit CO2 and expelled air
Here is the Elevation View of the Tunnel Complex ; at the highest levels are the Command Center, the Hospital and the Armoury. They are not directly linked so that there are routes to escape in the event one entrance is found out by the enemy. The Command Centre is only accessible probably near some river embankment or even underwater as shown on the extreme right. The people lived their entire lives underground for up to 20 hours each day.