Fighting a war against the United Empire, playing as a UE-flavored custom faction. Been sitting on a single enemy star system for the entire war; a good, 6-planet star, two star-lanes away from the UE capital.
Prior to starting this campaign, I read a guide the suggested that ships designed with almost nothing but kinetic weapons set for long range - the game itself explicitly states that kinetics are bad for long range and best for melee range. I've got seven destroyers and a corvette configured so sitting on this star system. They're lead by an admiral I accidentally hired(misclicked, was aiming for an administrator) at the very beginning of the game; they're somewhat aberrant, suicidal Craver with a specialty for defense named Storm Libera. As the war dragged on, I've been stacking as many defense skills onto it as possible as Storm leveled up.
The UE's latest and strongest attempt consisted of 10 ships(9 destroyers, 1 scout), with a total firepower slightly lower than my fleet. My fleet is moderately beat up at this point, so they've got a definite advantage. For the opening round, I played Barrier, but they countered with Adaptive Tactics. Despite that, 9 of their ships were obliterated in the first round, and the last didn't last a second into the second round. Their weapons did a total of 466 points of damage. Mine did
9289. My defense efficiency was 89%, meaning that the enemy did only slightly more than 10% of the damage they were supposed to.
Now if only this damn star system's siege defense wasn't so high I could actually conquer it in less than 80 turns(it is currently turn 81).
Endless Space. Good news, I have battleships on the way, including a design with over 1000 siege power.
EDIT: Suppressed the United Empire, and kept the Amoeba in check by holding a major choke point and not ever agreeing to open borders. The entire time, there was on faction I had yet to make contact with, though their game score was barely lower than mine. They decided to say hi. ...It was the Cravers. And they had a few fleets with over triple the fleet power I could muster myself.
The first actual battle against them, my fleet was ironically led by Storm Libera. I ordered an offensive retreat. I probably should have stayed and fought, since in the one combat phase I destroyed two of their ships and took only scratch damage. They tried to launch a ground invasion, which failed because I spent over ten thousand Dust on insta-building ground-defense structures on that system the same turn the Cravers made contact.
I also quickly redirected my science efforts, and a few turns and about 30k Dust for buying them, I dropped four Dreadnoughts on their face. They combined their forces into a fleet of nearly 20 ships with a total power of over 10k. That got erased in two combat phases, with my ships being immediately repaired(via Dust). Then the fleet that ran came back and finished off another 16 or so siege ships that had no ship-to-ship combat ability.
After that, I haven't yet seen any kind of threatening force to come out from the Cravers. I think I permanently crippled their force projection, and my counter attacks may have broken their economy. The Cravers can
not afford to be pushed back. Also, the increases to tax rates necessitated by the war is now giving me 1-2%/turn progress for an Economic Victory.