I think there are still some details missing from the explanation of how combat works. Here is another anecdote that Player One might be able to confirm if he reads this:

Last night when I logged out of the game, my opponent had a fleet of 23 cruisers orbiting the star of a system in which I had a colony. Given that I couldn't attack this fleet directly (because of the "no combat in star orbit" bug), I parked 26 cruisers at my colony, in addition to the 2 orbital laser arrays. This was a 400mu colony.

When I logged in this morning, his fleet was gone, my fleet was gone, and all of the orbitals around the colony were gone, but the colony was still mine. I assume he attacked with the 23 cruisers, although I suppose he could have mustered some more ships.

The outcome kind of surprised me. For one thing, it seems pretty clear that orbitals are targeted first. That's fine. But 23 cruisers have an ATK of 241. One laser array alone has a DEF of 300+, if I'm remembering correctly, and I think I had 2 (although it could have just been one). An additional 26 defending cruisers obviously outmatch 23 on their own. Then factoring in the 400mu planet, there is enough damage output on the defending side to obliterate 23 cruisers in one round, if combat works as recently described ( the "trample damage" analogy). So how is it that I lost all of my cruisers, all of my defense orbitals, and all of my non-defense orbitals in the battle? It doesn't add up if combat works as has been described here.

Player One, if you're reading this, feel free to fill in any details if it helps us understand how this game works.