I colonized an entire core sector and was just starting to build defenses there. I have a couple sullustan's, 2 gen core's, 1 laser, and 2 X-Wing squadron's in each system so far. The Empire sent a Star Destroyer into the sector and it's going around from system to system and attempting to engage my X-Wing squadrons. I withdrawl my X-Wings because 2 squadrons can not beat a Star Destroyer but the Star Destroyer never gets any damage. I would think that the Laser II on the planet that deals out 5000 in damage would be putting a hurting on this Star Destroyer but it seems to leave the system undamaged each time. Don't the system defenses engage an attacking Star Destroyer?

The planetary defenses only kick in when the enemy starts an Orbital Bombardment or a ground assault.

 

Ion Cannons are 'activated' when you as a defender, attempt to evacuate a blockaded planet.

Wow, that really sucks the big one. I've been putting a LNR Laser Battery II on each system figuring it would fire upon any raiding enemy ship. Is this a bug? Are my crews sleeping when that Star Destroyer just appears in orbit around the planet? Perhaps the screech of my X-Wings flying up to meet them can't wake the slumbering crews? It just seems odd to me is all.

The LNR batteries only fire when fired upon. (As Trej. pointed out) But are still worth having, I play as the Empire only- but I put more fighters on my planets- Twelve on core worlds and 3 or 6 on rim worlds: unless the rim world is important, then it gets 12. I also locate 6 troops on core worlds as well as 2 gencores.-Grand Moff Conway

think of it as the star destroyer has entered the system but is stand off from the planet outside lnr range. if it closes to assualt or bombard then it put's itself within range

The planetary defenses only kick in when the enemy starts an Orbital Bombardment or a ground assault. emphasis mine

I've never seen the LNR batteries open up during a ground assault...

I'm sure they did. They would always destroy or damage one of my precious ships while I tried to assault the planet.

Really? Wow...like I said, I've never seen that. It's been my biggest pet-peeve that my LNR's wouldn't fire upon invading Imps unless they bombarded.

really? an lnr opened fire on a ship during an assault? i've never seen that happen. i do know that lnrs open fire on troops while they're assaulting

The LNR does NOT fire on a ship during an assault. It does fire on the troops assaulting the planet. Try it out and see for yourself. Start a game and take a ship with troops to a neutral world that has 1 LNR on it and assault the world. You will see that one of your troops you assaulted with was destroyed but your ship has recieved no damage.

I agree with Starlightcoast. What I have obseved is that an assault with fewer troop units than exist on the target planet invariably fails (as one would expect). Thus, to defend a system with just two troops units leaves the planet vulnerable. I use the guide of the number to keep a system under control (usually minimum 6 ) and add one unit, usually defeats a troop assault.