how to manage large empire's border?

It gets real fun when your empire gets large and your enemys is not...and they can have the same fleet size you can.

You have to split your fleets up. I play the AI and usually have 2 fleets. One for defense and one for offense.

mmm... but then it usually happens that when they attack, their fleet is double as yours, so you have to move the 2nd as a backup from one side of your empire to the other

i think the limit in fleet size is annoying... it's not real that an empire twice or thrice bigger supports the same amount of ships as the smaller one

If a fleet seems too small and you have a large empire, I'd say you need to keep producing frigates and capital ships. Keep the gears of your military complex grinding and keep your rally points updated. That's my suggestion. Hope it helps.

Theoretically if you have planetary defenses up, you should be able to fight off a full sized fleet with less than a full sized fleet of your own, letting you split fleets. Just make sure you only fight with your half fleet at enemy planets without significant defense.

For me, the scenario is usually like you described; I'm off in a battle at an enemy system, and then an enemy fleet warps in to one of my planets. If I can, I finish up at the battle I'm in, either forcing them to retreat or destroying them. Then I just leave a cleanup crew there, and go help my planet.

You're right, usually you're too late to save it, but you might be in time if you had some defenses up to stall them. Either way, see if you can retake it, or at least prevent them from advancing any further. Of course by then, the first enemy you were fighting is usually trying to defeat the garrison you left behind at the original battle.

From my experience, this game is a big game of cat and mouse, with fleets jumping in and out trying to hit a weak spot. 1v1, the better player will usually win. If there are other players involved though, timing and luck play a bigger role.

maybe i expanded too quickly, without enough infrastructure, and the map doesn't help either...

Turrets and repair platforms built very close to the planet/asteroid (maximum overlapping firepower) are your friend in delaying until your fleet arrives and to support your defending fleet. Having planets behind your front line producing large amounts of culture so even if they kill your planet they can't colonize it helps as well.

If you are playing with two or more stars and the enemy AI is on another star try and control your star and the planets around it and eventually control the other star(s) the same way.

On my Planets near to enemies homeworlds I usually build 6-7 turrets and 2-3 repair platforms. If the enemy attacks and the first turrents got destroyed I immediately build new ones...they are not that expensive and can take a lots of damage. I destroyed a whole enemy fleet and his capital ship with this tactic without even moving my fleet to that planet (It was needed elsewhere).

If you are playing Epic size games against several AI's, I find you have to identify the chokepoint worlds that you expect to have to hold out while you are expanding somewhere else. I fortify those worlds very heavily.

In addition to my main expansion fleet, I have a couple of small picket fleets. These fleets are solely to augment the heavily fortified worlds....with a little bit of micromanagement, a small fleet can do wonders against a larger fleet when it is backed by repair bays and 20 turrets + hangars. On top of this, I have frigate factories stationed on (or near) the frontier to constantly rebuild those picket fleets as they get chewed up.

If a REALLY determined force attacks a world and can overwhelm these defenses, they usually are held off long enough for my main battlefleet, or another defensive fleet to get there.

This is what works for me...of course, before I started locking the AI teams, all the remaining AI's would be allied against me by the end of the game, and this DID make things kind of interesting.

Thanks for your help!
I started a new game yesterday, 3 stars, 50 planets, 8 opponents. I made better moves this time and fortified chokepoints much more than i used to do before. Result: success! I've succesfully conquered 3/4 of my star system already, have a strong economy and the biggest fleet. Let's see what happens when i face a second star system

VS the AI

1) play vasari
2) build a small number of repair bays, turrets, and hangers
3) build 1 phase stabilizer, 1 phase jump inhibitor, and 1 nano jammer at each choke planet
4) build subverters with distortion field
5) the trap is baited and set, pray the enemy sends his whole fleet
6) once he jumps in, send your fleet over. 1/3 the size of his fleet will do the job if it has 10 subverters.
7) The slaughter begins. Disable everything and dont let a single ship return home
game over

I'll try that later. So far, I've been playing TEC. Once I know all the secrets of this race, I'm gonna switch to Vasari.