00:00Ancient Hellenistic trench defenders face silent subterranean murder right beneath their muddy boots.
00:07How did engineers detect enemy tunnelers hacking through solid rock feet below the surface without modern radar?
00:14Common Sense says guarding troops should just listen with their bare ears, but solid dirt blocks all sound.
00:21Suspended bronze vessels acted as acoustic amplifiers vibrating whenever enemy pickaxes struck subterranean stone far below.
00:30This metal resonance trap proved that ancient Hellenistic trench defenders faced silent subterranean murder right beneath their muddy boots.
