This episode tells the story of SS Atlantus, one of the U.S. emergency concrete cargo ships built during World War I, and explains why the government turned to concrete shipbuilding when steel and shipyards were scarce.

It follows Atlantus’s launch after the Armistice, her grounding off Sunset Beach, New Jersey, and how the wreck became a local landmark and a reminder of how crises reshape technology and leave fragile traces of history.