A CCF fire team mans a 7.62 mm Ruchnoy Pulemyot DP (Degtyaryova pakhotnyi) in a front-line cave.
When truce talks began, China spent a year rebuilding their armies, constructing an underground system of interconnected caves and tunnels behind their main defensive lines, in such strength as to be invulnerable to our artillery except when they sent forces above ground to attack our outposts. By July, '52, the enemy lines were virtually impregnable, except for their own outposts. Even in those outposts, the Chinese and North Koreans dug deep cave systems behind their trench lines, making any assault very costly.
Even with her large manpower resources, it was an awesome accomplishment for China to build the interconnecting cave-tunnel complex which supported her main-line defenses. ("A total of 1,250 km. of tunnels and 6,240 km. of trenches involving the shifting of 60 million cubic meters of rock and earth were dug along the front" - Marshal Peng Dehuai)
