You're right, this might need to be a new game. Emphasis on might. I'm reserving judgement until I see
Skyrim in action.
Still, let us not confuse Nafaalilargus with the dragon you get in
TES V: Skyrim. The first was an actual beast, one that could be, as was, killed. Once gone, it wasn't coming back.
In the new game, and based on developer comments, we're talking about the Jills, basically divine spirits that are servants of Alduin, and after you kill one of their number, you learn his True Name, meaning you get to use Thu'um to summon that one to do battle for you. Which means yes, you have one dragon. But you continue to have one dragon.
It could play along like this:
QUOTE
Soldier for the Dovahkiin: "Sire, the dragon is down. It took over 100 battlemages, but they brought it down."
Dovahkiin (Me!): "Eh? Oh, yeah, figured that might happen occasionally. Surprised it took this long, really."
Soldier: "Sire, we've lost our dragon. And now their battlemages are turning fire at our army."
Dovahkiin (Me!): "Easy. They may have underestimated my Power. Check this out."
(Breathes in real deep. Then shouts, in Dragon Tongue): "OY! (Insert Name of Dragon Here)! BACK TO WORK! KILL THOSE BATTLEMAGES! AND THEN TAKE OUT THEIR TOP COMMAND!"
(Said dragon reappears, sort of like recasting a summon spell after ally was destroyed, except it's a giant fire-breathing flyer. It lays into the unsuspecting battlemage corps and turns the tide of battle.)
Dovahkiin (Me!): "There, that should about do it for today. Which province are we 'Re-integrating into the Empire' next week?"
And that's on the low end. If you're gonna be fighting, and stopping, Alduin, I could imagine it going some more like this:
QUOTE
Soldier for the Dovahkiin: "Sire, the dragon is down. It took over 100 battlemages, but they brought it down."
Dovahkiin (Me!): "Eh? Oh, yeah, figured that might happen occasionally. Surprised it took this long, really."
Soldier: "Sire, we've lost our dragon. And now their battlemages are turning fire at our army."
Dovahkiin (Me!): "You're right. They may have underestimated my Power. Time to up the Ante. Check this out!"
(Breathes in real deep. Then shouts, in Dragon Tongue): "OY! ALDUIN! I'LL LET YOU OUT FOR HALF AN HOUR! TAKE OUT THEIR TOP COMMAND! BUT LEAVE THE REST! A GOOD ARMY IS A NICE THING TO TAKE AS PLUNDER!"
(Alduin appears. That's right, a frakkin GOD appears to do battle! A giant, fire-breathing, really hungry god.)
Dovahkiin (Me!): "That should teach them not to F@ck with a Dragonborn. We're so bada$$, we bring gods to a mortal fight. You alright, son?"
Soldier: "I may need a drink, Sire."
Dovahkiin (Me!): Well, we are now a week away before our next 'Re-Integration into the Empire.' Who is next, by the way? Anyways, I believe I could now spare the men a night of drinking and whoring. Have fun. Though, send any of the really good-looking red-headed wenches my way. Service to the Emperor is well rewarded."
Just saying that the bloody Dragonborn deserves a bloody empire. And besides, given the whole Dragon-motif of the Cyrodiils, and the fact that the Dovahkiin bloody well saved Skyrim, getting large-scale support shouldn't be too difficult from those two provinces. And it becomes less of my "group of volunteers" and more like "The Legions of the Dragon!" One indicates possibly a few thousand troops. The other indicates several hundred thousand soldiers, well organized, equipped, and trained for campaigns of reconquest.
I agree that it's one thing to rule Skyrim, and quite another to rule Tamriel. But you build on your success. The Blades in Skyrim under Esbern (or appropriate sucessor if the old mentor dies) form your newly reformed Imperial Order of the Blades. You make the expansion more about diplomacy and tact, strategic engagements and a gathering of support like the Hortator quest in Morrowind, but with the effect of building a Legion like the Allies for Bruma ques in Oblivion. You meet with various nobles, kings, guild leaders, etc., and get their support for your cause. You already have all of Skyrim behind you. Take Cyrodiil next. Use the troops to create a professional, prepared army, defeating political opposition at the head and using the body of support as your own. Build a reverse Hydra, if you will, by eliminating the leadership of your rivals and adding their strength to yours.
When you must engage in combat, engage with a strategy that serves your overall goals. Offer terms to those that submit, quarter to troops that defect, position to those that come ready and willing to adopt your banner. Exterminate those leaders you must, bring down the heads of any organized enemy, scatter to the winds any force of fanatics that oppose you. And when the day ends, know that those you gaze upon today will support you, so that the enemy you face tomorrow has already lost his crown.