Military engineers seem to often be misunderstood or disregarded by new players - which is fair, as they do not look very useful at first glance. However, they’re one of most crucial units in the late game, and you should always plan to use them. Here’s why and how. Introduction Disclaimer: this guide is mostly suited for players who have the Gathering Storm expansion, as most of Military Engineers’ uses come from there. I think we can all agree that Civilization is a pretty dense game, and it’s easy to miss out on some specific points in one’s first hours, like how to build a dam or how to create Apostles. That said, one thing that particularly strikes me out is the utility of Military Engineers. They are one of the best units of the game and are absolutely essential to benefit from key upgrades in the later eras of the game. This is not immediately obvious however, as Military Engineers have very precise requirements to be created, and start with very few skills (or uses). What the game doesn’t really tell you is that they will gain other as you progress through the tech tree, and you will absolutely want Military Engineers in the Industrial and later eras. Why use them? What are military engineers?Military Engineers are support units. However, unlike other support units, they do not provide passive bonuses to nearby military units. Instead, they behave like builders and can be used to build, repair, and remove improvements. You should note right away that Military Engineers spawn with only two build charges. This amount cannot be increased by any building, wonder, or policy. The only exception is England, whose engineers spawn with four charges. Like builders, they can: repair or remove tile improvements (free) remove features and harvest resources (1 charge) clean Nuclear Fallout (1 charge) They also start with the ability to build Roads and forts, each at the cost of one of their charges, which is pretty terrible. Roads are better built by traders, and forts aren’t all that useful, at least in lower difficulties. As you progress through the tech tree, Military Engineers will gain the following skills: build railroads (free) once you unlock Steam Power build mountain tunnels (1 charge) once you unlock Chemistry build airstrips (1 charge) build missile silos (1 charge) Finally, they can spend one charge to instantly complete 20% of the construction of Aqueducts/Baths, Canals, Dams, and Flood Barriers. Some of these uses should immediately seem more appealing. We’ll see in more details below how it benefits you and your empire. How to build them (and plan ahead)Military engineers can only be created (or purchased) in cities with an Armory, which means having first built an Encampment and a Barracks or Stable. Building an Armory requires the Military Engineering tech, which you will want sooner or later, as it reveals Niter on the map. You should build an Armory at least two cities (or more, depending on the size of your empire, but having two reliable sources of Military Engineers is a good start) once you have this tech. You don’t need to build Military Engineers right away (unless you want forts), but you should be ready to build them ASAP. If you can create one or two engineers and store them away for later, that’s always a good bonus, but as long as you’re still in the Medieval/Renaissance eras, you don’t need to postpone other productions for the sake of engineers. However, when you start to get close to the Industrial era, and specifically, to the Steam Power **tech, which unlocks Railroads, you will want to start producing some Military Engineers if you haven’t already. How many?That mainly depends on the size of your empire. You will want to connect all your cities with railroads; the greater your empire, the longer it will take. While building railroads do not consume your engineers’ charges, it obviously is faster to build your whole train network if you have several of them at work. The other factor to take into consideration is whether you’re in active conflict (or plan to start one). Military Engineers can help your armies with defense (forts), movement (railroads), and bases (airstrips and silos). How to actually use them? Logistics - ConnectionsUnless you absolutely need a road built (to help an army reach a remote location), I would never use Military Engineers to build regular roads. This is way too expensive, and traders do that well enough. Railroads, on the other hand, are both free and exclusive to engineers. They are the best kind of terrestrial road in the game, and also bolster trade. You want to have a network of railroads in your empire, at the very least between your main cities, if not between all of them. This will generally allow all your units (builders, military…) to reach their destination faster. You have to move an engineer and build the railroad on each tile, which is a bit of a pain, but it is worth it. Usually the quickest way to do it is to follow the roads previously created by your traders, but you can build railroads to anywhere you like. Keep it mind, however, that they cost iron and coal (which means you’ll be generating CO2). The other structures you will want to build to connect your cities are mountain tunnels. The title is self-explanatory. Aside from the obvious, you should know that mountain tunnels are connected if they’re in the same mountain range. So, if you have 10 adjacent mountain tiles, you can build a tunnel on each end of the range, and have units instantly move from one side of the mountain range to the other. Mountain tunnels also bolster trade like railroads, and are extremely useful to navigate around the map quicker. Logistics - Repairs and efficiencyMilitary Engineers can also be used to repair damage. Builders usually end up disappearing, because you just always need their charges to build something here or there. You can always store a builder in a city where you regularly need to repair damage (flooding and volcanoes are the most common sources), but I’d rather do that with an engineer. At some point, you will have built all the railroads and tunnels you need, and your unlike builders, your engineers can pretty much go chill somewhere - you might as well have them ready for repairs. Military Engineers are also great at speeding up the building of critical structures, as listed prior. It is particularly useful when you start building Flood barriers. Flood barriers will protect you from the rising of the seas (which will happen sooner or later, even if you avoid building Coal, Oil or Nuclear power plants, as modern units and railroads also generate CO2), but they can be very slow to build, especially in newly founded cities with low production yields. In such cases, instantly completing 20% of the construction helps a lot. The sooner your Flood barriers are up everywhere, the better. You want them built before the sea levels rise - even if flooded tiles can be recovered to a degree, avoiding the flood altogether is much better. Military supportThe last way you can use Military Engineers is to support your army. They can provide some help on the defense (with forts) or to attack other civilisations, mostly by building railroads and help your army advance, or mountain tunnels for a “surprise attack” through the mountains. In the later eras, you can also use them to build airstrips and missile silos. This is particularly useful to redeploy aircraft or missiles from cities that lack the necessary infrastructure, which again, can serve both your offensive and defensive needs.