John C. Chapin, Breaching the Marianas: The Battle for Saipan
“ The enemy had defended caves before, but never on such a large scale. On Saipan, these caves were both natural and man-made. Often natural vegetation gave them excellent camouflage. Some had steel doors which could be opened for an artillery piece or machine gun to fire, and then retreat behind the door before return fire could take effect. The flame-throwing tanks could reach many of these caves and so proved very useful. ”
