Heh. I just had an interesting war. The aliens surrendered (under my terms for them to become my vassals) to me while we were in the middle of a fleet flight that I was losing. I guess I got enough of their ships down for them to consider surrender in the middle of the fight.
It was actually really fun. My ally was on the opposite side and waged a 2-front war. Not sure how much my ally did, but they definitely helped distract enemy fleets while I occupied one of their border worlds. I then made the mistake of sending my 850 power 1st Expeditionary Fleet into one of their core systems.
In comes a 2k power fleet. I retreat to the occupied system, send away my troop transports and bring in my 400 power 1st Response fleet. Luckily the 1st Response Fleet arrives just in time as the enemy 2k power fleet begins engaging the 1st Expeditionary Fleet.
Battle actually went fairly well, considering the odds. I managed to put a serious dink in their fleet (though admittedly I lost something like half of my Expeditionary Fleet.) I then sent my Homeland Defense Fleet from my Homeworld to my territory's frontline, where I regrouped my Expeditionary and Response fleets.
I then merged the three fleets along with some new ships from my Homeworld.
My combined 1st Emergency Fleet was still fairly underpowered. 1k power compared to what I think was a 1.8k power enemy fleet. I consolidated the rest of my fleets into the 2nd Emergency Fleet which was placed in my territory's frontline. (The map here is actually pretty interesting - both of us use hyperlanes, and there's only one hyperlane to each others' territory. On my side I have a basic Defense platform and Frontier Outpost. That's what I referred to as my territory's frontline.)
The 1st Emergency Fleet then was sent to raid one of the enemy's core planets. I managed to destroy a couple new destroyers of theirs along with their shipyard. Managed to book it before the enemy's 1.8k fleet arrived. After this I then finally combined the 1st and 2nd Emergency Fleets into the 1st Emergency Fleet.
Hoping to put a serious dent into the enemy's fleet while I created a new fleet back in my territory, I sent the 1st Emergency Fleet back into enemy territory, where they engaged the 1.8k power enemy fleet for the last time.
Battle wasn't going too well - a good third or so of my fleet was destroyed with way less enemy casualties. But in the middle of it the enemy accepted my terms and became my vassal.
That was actually really fun. Even if it isn't practical, I do love naming and organizing different fleets. (Prior to the fighting, I had 3 main fleets - Expeditionary, Homeland Defense, and Response. Response was a small fleet originally placed at the frontline before the war to act as a first response unit. The least powerful fleet. Homeland Defense is pretty self explanatory - a fairly standard fleet that more or less just sat at my homeworld for general territory defense. Wasn't powerful, per say, but the intent was to do serious damage and hold out until the Expeditionary Fleet arrived. The Expeditionary Fleet was basically my main one. Most powerful, most ships, was the invasion fleet, etc.)