The Pentagon have announced plans to prepare for wars in megacities such as New York by building huge underground military bases. The U.S. government have said that a war in a major city is likely to be fought underground and have asked technologists to come forward to help them innovate and prepare for such a scenario. Popsci.com reports: Megacities are a relatively new phenomenon. When the Marines stormed the Halls of Montezuma in 1847, the entire population of the United States was just over 20 million. Today, 20 million people live in or around Mexico City itself. Underground transit systems are also pretty new. While Union and Confederate troops were fighting at the Battle of Arkansas Post, London’s Metropolitan Railway began operation for the first time. Today, there are at least 148 underground transit systems in cities across the world, and with them, lots and lots of tunnels and alternative routes through cities. Fighting a war in the future may mean fighting in a giant city, and it may mean fighting literally underground. From the Pentagon’s solicitation: As the world’s population grows, the probability of the U.S. needing to conduct combat and humanitarian assistance / disaster relief (HA/DR) operations within a megacity [...]