The Tunnels:
Due to the incredible pounding given to the Japanese base at Rabaul by aircraft from the air forces of USA, Australia, and New Zealand the Japanese defenders simply "dug in"!

The pumice hills of Rabaul were honeycombed with over 500Km of tunnels, including 15 hospitals (one such being 4Km in length, and having capacity for 2,500 patients). Indian P.O.W's captured at Singapore, and local inhabitants were used as labour for digging the tunnels - extreme hardships and many deaths resulted.

The Barge Tunnel at Karavia - 5 Barges (4 Views)

Also see Rabaul - FORTIFICATIONS for more info on Tunnels. 

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