Editing BattleTech (section)

==Warfare in the Thirty-first Century==

When somebody decides to attack another world, they load up their 'Mechs (and tanks, and infantry, etc...) onto massive shuttles called [[BattleTech_Spacecraft#DropShips|DropShips]]. These boost off into space and link up with JumpShips, semi-mobile Space-Fold drives sitting a ways out into the star's system (due to the limits of BattleTech FTL, JumpShips can't get any closer to a system's star than a radius roughly around the orbit of Saturn in the Sol System. For simplicity's sake, most JumpShips move to the zenith or nadir points directly "above" or "below" the star's orbital plane). The DropShips latch onto the JumpShips, which make a series of jumps from star to star until they reach the target system. 

Compared to some sci-fi franchises such as Star Wars or Star Trek, aerospace combat between ships isn’t really that common for several reasons. For one, KF Drive used to propel JumpShips (all of which can’t land on a planet) makes up 95% of its mass and leaves little room for anything else besides DropShip docking ports, basic ship equipment, crew quarters, and the Jumpsail used for recharging the drive. And while Warships do exist with drives half the size as their civilian models, the drives alone are more than five times more expensive to build and are prioritized for only strategically-vital missions, like real-life Dreadnoughts. In that regard, BattleTech’s JumpShips are closer to Dune’s massive but ungainly Heighliners, which transport combatants between stars and planets, but lack any inherent ability to fight, than Star War’s Star Destroyers, which are capable of both transporting combat units between stars and planets and are themselves capable of fighting. As a result, most aerospace combat is dominated by armed DropShips or aerospace fighters. Orbital and naval blockades are a thing but not typically used frequently due to how much firepower is required for a planetary scale.

Once they reach the destination (normally the "northern" or "southern" jump points of a star), the DropShips detach from the JumpShips and burn deeper into the system towards the targeted planet. Now JumpShips aren't stealthy, so anyone on the target planet likely detected their entrance into the system, and it typically takes DropShips seven days (varies dramatically for each star system) to reach the planet. Surprise attacks are nearly impossible, and defenders will have up to a week to get ready (some clever, smart, or just plain foolish people try to shave time by trying to match the target world's orbit with a nonstandard point closer to the planet, or even rare "Pirate" points caused by gravitational interactions between celestial bodies, but even this usually gives defenders at least a day to prepare, not to mention the hilarious habit of Pirate points to just mangle JumpShips attempting to use them beyond recognition).  In reality however, points in space where gravitational forces balance out aren’t actually rare (they're called [https://en.wikipedia.org/wiki/Lagrange_point Lagrange points] in real life) and there are five of those null-gravity points just for the Sun-Earth system, along with five more for the Earth-Moon system, and five more again for every other pair of celestial bodies orbiting each other that you care to name. Those points can be so close to destinations of strategic interest that by BattleTech standards, it would take probably just a few minutes to reach the Earth from one of its own null gravity points, seeing as BT DropShips can reach Sol's zenith (the Sun's "northern" null-G point) or nadir (the Sun's "southern" null-G point) in just a few days from Earth, i.e., crossing more than the distance of one Astronomical Unit, or 150 million kilometres, in a strategically-insignificant amount of time.  

As the invading force reaches planetary orbit, the defenders will usually try to intercept them with their own defensive ships, usually DropShips, Shuttles, Aerospace Fighters, and Conventional Fighters (like the [['Mechbuster]]) while the Attackers will launch fighters of their own. Space battle will begin in earnest as the defenders try to keep the enemy from landing on world at all (FASA originally had two separate games, Aerotech and Battlespace, that dealt with this stage of combat, but current BattleTech rules incorporate Aerospace combat for those who prefer it or want the full Theater of War experience). 

If the Attackers can break through the orbital defenders, they can choose their landing site (usually near the target of course) and deploy either via a combat drop with [[Drop Pod|Drop Pods]] launched from DropShips or via DropShips landing at a secure LZ. The enemy will deploy to stop them and battle begins in earnest with ground combat typically consisting of combined-arms use of infantry, battle-armored troops, conventional armored vehicles, artillery, and BattleMechs. Meanwhile, any air assets in the form of aerospace or conventional fighters will duke it out to secure air superiority for shipping reinforcements via air drop, or trying to take out enemy ground units from above.