Subspace Combat

In subspace combat the nature of the environment makes missiles useless. No matter how good their engines a missile effectively travels no faster than any other vehicle. This makes them easy prey for energy weapons.
Like missiles, railgun projectiles are really just matter enhanced with gravitational engines. They tend to lose momentum quickly and become ineffective at any kind of range.
Energy weapons ranges are drastically reduced, but their effectiveness within their useful range is unimpaired. Typically energy weapon ranges are reduced by 20, that is they are half as effective as they are in normal atmosphere.
Force fields are just as effective in subspace as in real space, but as a gravitic phenomenon are less detectable in the high gravametric environment of subspace. In other words a ship protected by a standard force field is harder to detect. Against the high gravometric background of subspace force field stealth technology is less effective.
On balance this makes it hard to detect protected warships at greater ranges, but distortion fields and masking are less effective at close ranges.
The heavy electromagnet interference in the subspace environment makes long range and active sensors not nearly as good as in real space. This is one reason road beacon stations are seeded so close together and why off road vehicles and ships must depend upon inertial navigation and gravitational topology plotting and can only detect subspace beacons when they are fairly close to the system that has anchored them. This also makes the kinds of weapon ranges seen in real space battles untenable in subspace. Because of the high EM background EM masking and stealth become more effective.
Once away from the beacon stations of the Major Routes and Blue Highways accidentally meeting another vessel is unlikely. So battles in subspace tend to occur at gates or near system beacons. Of course this is where systems concentrate their own defenses when they expect an attack as well as where standard defenses are anchored.