61 Cygni, the system of Doom.
Adjacent to Sol it was infested with a serious case of precursors , and I have met a friendly NPR there, fairly certain it is not their home system. After 18 years and the destruction of 2 Battle fleets (14 and 22 ships respectively), my 3rd fleet goes in and wipes them out with the expenditure of 90% of its missiles , then as I don't have a jump ship for the 3rd generation large ships (20,000 tons) they retreat to the JP to wait for a Gate ship to build a gate. Survey ships enter and salvagers as there are a lot of wrecks here. First Survey ship jumps out to Wolf XX and encounters the Invaders and a lot of wrecks (I suspect this may be the friendly NPR's homesystem oops), so runs away . 5 days before the jump gate to Sol is finished 3 invader ships enter the system and wipe out my fleet 18 ships who can't put up any realistic defense as they have no missiles left and 20cm lasers on the 2 energy combatants stand no chance against Invaders and their ECM.
A 4th fleet is under construction in Sol in the hope that it will be finished before the invaders arrive, apart form that I have 2 Hab 0 planets in Alpha Centauri and 61 Cygni and a bunch of other planets which could be terraformed and excellent mineral deposits in several systems near Sol.
There are plenty of spare missiles on Earth, probably not enough to kill Invaders in an open space battle but enough so my fleet would have died fighting, of course no Missile collier had been built and most of the missiles were fired from Box launchers so no practical way to rearm the fleet in 61 Cygni
Fortunatly the Invaders never got around to invading Sol instead they have built up a huge fleet (123 ships) in 61 Cygni . (All orbiting an uninhabited world, I have no idea what they were interested in but they spent years their letting me build a fleet) After a few encounters with groups of their ships I have built up to a fleet of 158 ships backed by 140 fighters (ranging from 18000-50000 tons) and have gone after them. So far I no damage has been done but I believe I have survived all their long range missiles and am currently shooting my way through their AMM salvo's 511 missiles per salvo , no hits so far as I have a lot of Gauss cannon. When they have run out of missiles we will see if I have enough missiles to kill them, if I don't then their 50cm lasers will probably cut my fleet to pieces.
I think this is the largest battle I have fought so far , the scaling effect is interesting I don't think any previous fleet of mine could have survived the AMM bombardment as I just would not have had enough guns to shoot them all down.
I lost 2 ships in the battle both to ramming attacks, my missiles killed all their beam armed ships. I would probably not have managed that if they had held their antimissiles back to shoot down my missiles. However the combination of fast ships, ECCM and heavy armour made them difficult to kill with lasers and gauss cannon. My losses were limited to 2 ships as I had 5 Decoy ships along (200k commercial hulls stuffed with armour) I had meant them to absorb missile fire but they were largly ignored . But they absorbed ramming attacks by most of the enemy missile ships.
Interestingly a couple of the armoured ball ships survived ramming attacks and gained a crew quality in the 90's because they took so much damage. Sadly I lost the database not long after the battle (I was setting up another game at the same time, and cleaned out a couple of mistaken setups AND my ongoing game by accident )