> magine you could go back in time to the ancient world to jump-start the Industrial Revolution. You carry with you plans for a steam engine, and you present th

> magine you could go back in time to the ancient world to jump-start the Industrial Revolution. You carry with you plans for a steam engine, and you present them to the emperor, explaining how the machine could be used to drain water out of mines, pump bellows for blast furnaces, turn grindstones and lumber saws, etc. > But to your dismay, the emperor responds: “Your mechanism is no gift to us. It is tremendously complicated; it would take my best master craftsmen years to assemble. It is made of iron, which could be better used for weapons and armor. And even if we built these engines, they would consume enormous amounts of fuel, which we need for smelting, cooking, and heating. All for what? Merely to save labor. Our empire has plenty of labor; I personally own many slaves. Why waste precious iron and fuel in order to lighten the load of a slave? You are a fool!” That's not the correct sales pitch to use with an emperor. The correct sales pitch is to show him how he can win battles. Throughout history, until the 19th century, a lot of military confrontations ended up with a side hunkering down in a castle, and the other one sieging that castle. Most sieges were unsuccessful and the successful ones were costly. One of the methods used during sieges was the undermining: you mine a tunnel from a safe distance until you get under the fortification's walls, and there you enlarge the hole until a part of the wall collapses. Of course, this only works if the tunnel you dig does not get flooded. If it gets flooded, you're out of luck. But put a Newcomen engine there, and your attackers can keep digging inside dry tunnels. Who can stop you now?