At the very end of 1838 (western calendar), that last decisive battle at Savannakhet brought us even with Dai Nam in warscore. In fact, we're actually ahead 0.2 -- the last battle basically having undone everything the Dainamese had accomplished to date.
Time to take the battle to them! My first move is cautious. I don't know for certain that they have nothing left to fight with (and we find out later they do!), so my moves are guardedly aggressive -- I move into Vinh with our largest army, and send the remnants of another brigade into Vientiane. This has the effect of blocking any counterattacks -- with the fronts as they are (with Cambodia not yet in the war) nothing can get past those two provinces. Once my guy arrives in Vientiane, he'll move from there into Thanh Hoa.
My move into Vinh is also aggressive because I'm following the enemy. We won a great battle, but allowing him to escape would be foolhardy.
Multitasking -- always, even during war! -- I improve my relations with my neighbor the United Kingdom, just in case they have any designs upon my territory. The better our relations are (they're not high enough yet, but I'm building the bond), the more is at risk (Infamy, Militancy) if they decide to attack me (which means they won't -- they'd give warning by reducing relations first).
As expected, the followup battle at Vinh was short and forced the surrender of the entire enemy remnant for little cost to me. I leave a small force to begin taking control of Vinh, and move my largest force north to start seizing Thanh Hoa. As soon as my army in Vientiane rests a little (he's really sapped!), he'll move along too.
It really does appear as if there are no enemy armies left (only a couple being recruited -- the little guy in the white shirt at Hanoi, for instance), and so I leave another small holding force to siege Thanh Hoa while moving my main force north to their capital at Hanoi. If, by some odd circumstance, they still have an army up there, I want my largest force (unfortunately just 2-3,000 strong) at the front.
I get an event in the meantime. It's basically a choice between some POPs gaining MIL and CON and earning extra research points, or nothing happening and losing the same number of research points. I don't remember if I mentioned a similar event earlier. I handle this the same way. Even though I'm not particularly keen on CON for non-Thai POPs I don't want to lose 2 months worth of RPs so I accept the penalty that earns more.
My economic situation is never entirely outside of my attention span, even during wartime. I'm concerned about my Artisans -- some of them are still starving, and they're becoming some of my most Militant POPs (and I can hardly blame them, though I wish they would pick better Goods to make, as some of their brothers are doing okay).
I lower their takes as low as I can with a conservative government, and even lower tariffs to 15% (from 20%). This still leaves us a small positive daily balance.
As the spring season rolls on, we continue to take territory (gradually - represented in the game as a percentage of the province controlled), and to spread out our occupation. We've moved a brigade into Hue, now.
Strangely, it's now that Cambodia decides to enter the war. Dai Nam has finally asked them, and it's difficult for them to say no, since they're a satellite. They may be thinking this is their last gasp, or that they can destabilize our occupation by opening a second front where we don't have any troops.
I do already have a regular infantry brigade in service. I begin recruiting another in Bangkok -- the Cambodians won't have time to reach our capital before this brigade is ready, and I expect he'll be able to hold off one or two brigades of Cambodian irregulars, just by himself. I'm not terriby worried, even as Cambodia's three brigades march into Battambang and begin trying to take control of it.
Meanwhile, as summer begins, I've succeeded in taking Vinh and Thanh Hoa, which frees up armies to begin running south to meet the Cambodian incursion.
One of the brigades under construction in Dai Nam (there's a second in Hue) finished building, but since I had my army sitting there the new enemy brigade was caught with no organization and immediately forced to surrender (because if you have literally 0 organization and are defeated, you must). The same will happen in Hue once it finishes recruiting. This can be disastrous for a country with no active armies, as they can lose those under construction too, as we're seeing here.
I'd begun spreading my occupation south, into Tourane, but once I got there I could see there must have been a third recruiting brigade hidden by fog of war, because he's coming north from Pleiku, and will arrive by the beginning of July.
I'm in luck that I can make it back to Hue before the enemy reaches Tourane. The two low-strength brigades might be able to hold him off if it comes to battle. Unfortunately, Hue has plains as its terrain, which has no combat modifier. Tourane would have added a modifer for its jungle, but I think my odds are still better reinforcing in Hue rather than waiting in Tourane with a smaller force.
The battle is joined in mid July, and it almost seems as if I might succeed in beating him back because he has low organization (newly created units have this problem). But his die rolls are good, and I can't hold. By July 18 he somehow manages to totally defeat me (all of my brigades surrender). His die roll was good enough he may have actually destroyed most of my unit in the first round of combat (I was losing 400 troops per day), and had little left to stand against him in the second round, which would mean I'd lose no matter what my die rolls were.
This is a setback, but not a decisive one. My larger army has left Haiphong's occupation for another day and is rushing south to plug the gap. The enemy won't be able to move into my territory, or even to reverse my gains.