In the Cold War, the U.S. faced a terrifying military communications problem: how do you send orders to a nuclear submarine that is fully submerged and silent? The answer was one of the strangest engineering projects in American military history—Project Sanguine, a plan to build a massive 28-mile antenna system capable of transmitting extremely low frequency signals through seawater. This is not just war history. It’s military engineering at its most extreme. Project Sanguine was designed to create a survivable communications network that could still function after a nuclear strike. Engineers proposed burying thousands of miles of cable, building transmitter stations, and using the Earth itself as part of the system—an ambitious attempt at long-range radio warfare and strategic command control. In this military history documentary, we break down how this wartime innovation worked, why it

Source: The U.S. Built a 28 – Mile Antenna to Talk to Nuclear Submarines