I want to share with you what happened in my last game.
I had to attack one of the AI homeworlds: I destroyed all guard post and only the AI command station remained, but it was protected by a mkIII fortress and by two mkV forcefields.
I'm still a noob (this is my second game) so I was unsure how to handle this. I discovered that fortresses have a 0.01 multiplier against polycristal ships (bombers, mainly) so I kept all other ships out-of-range of fortress and sent my bomber alone to attack it.
It worked quite well until AI started sending fighter against them... a lot of fighters... I retreated close to my other ships, but most bombers were gone by the time I reached the main fleet.
I retreated and after 10-15 minutes I gathered enough forces and tried again. This time I brought space planes together with bombers: their radar dampening range was enough to keep fortress to fire against them while defending bombers, but again hordes of fighters stopped my effort.
It happened again and again and again, so I decided to change plan: I brought an hacker and put a sabotage hacker there. I defended it for 1 minute and fortress was gone, another minute and the first forcefield followed. Other five minutes and everything was over.
Now I have two question for you:
don't you think that, using sabotage, everything resolved in a too easy/fast way? hacker itself is not very expensive, and cost for sabotage is very low (in my case it was less than 10).
or it was just my experience?
finally, just out of curiosity, how would you have solved the situation? Is sending bombers alone/with space plane (when available) a viable solution? Any other idea?