Europa Universalis: Rome
This title is one of the odd dogs in the series. It is far more character driven than even, say, Crusader Kings, but actually getting a good sense of what's going on at any given time amongst the dozens of important people in the court of your country is like herding cats. So, not at all inaccurate at least.
This string of bad lucks comes from a mechanic that says, basically, regiments of soldiers that are frequently lead to victory under a general will become loyal to that general over time. This means, that it doesn't always pay to have the best general in charge. Why? Well, I'll get to that as part of the string of bad luck.
I started up the grand campaign, the Fledgling Roman Republic is set to conquer the Greek city states that sit on the bottom tip of the peninsula, Magna Graecia, and from there, at least a portion of Sicily. It also sits at war with Epirus, and Pyrrhus the Great sits across the Adriatic Sea, his extremely high martial talent making me a tad nervous, despite the paltry size of his army. In this game, Martial Skill counts something like twice as much as it does in, say, Crusader Kings, for comparison, if you've played it.
I have an army of over twenty thousand, and appoint the best military minded character I can find in the court of Rome as general. It consists of a few archers, a few light infantry, and mostly heavy infantry. No Calvary, as horses are unfortunately a bit tough to come by in the peninsula. The nearest source however, is near Epirus, and I make it my plan to conquer that country, and move on to conquer the other petty states that dot the Balkan Peninsula all the way to Thrace.
There are a few problems with this. A complex web of alliances and guarantees amongst the despots of the peninsula meant declaring war on one was tantamount to declaring total war on the whole peninsula. This isn't really too bad, though, as the army I can muster, and the general I put in charge of it, is certainly enough to scrape by, and in the mean time, I can begin organizing a second one, as I have the manpower and money to spare, and will only have more after conquering a few of those states, and with a few cavalry divisions this time.
Thus, after subjugating Epirus and throwing Pyrrhus the Great in prison, I declare war on the Illyrians, and consequently, the rest of the peninsula, with confidence. The armies that move upon my general's army are fairly small and are all routed and destroyed one by one. If they had operated on a cohesive scale there might have been trouble, but since they presented themselves in easily digested chunks, things went smoothly and I was able to begin occupying territories while they rebuilt their armies. This goes on for a while, in cycles, and I fail to notice that every single unit in this army is now loyal to the general, whose victories are beginning to give him a bit of a delusion of grandeur.
At the conclusion of this great war, the whole of the Adriatic Coast, and most of the Greek States have fallen under my thumb, annexed. The Roman territory over the course of this conflict possibly doubled in size. Then I notice something. As my second army is in the process of being built, a huge horde of Barbarians appears on the fringes north of Italy on course straight for the heart of Rome. I mobilize the small second army and begin moving it to intercept, and order my experienced army under the great general to get on board the boats that took him to Greece and return to Rome and drive off the barbarian horde.
His Reaction? He proclaims himself Consul.
The whole of the territory that he conquered, all of Greece and Magna Graecia flips over to Roman Rebels, and that general, with all his elite veterans, and his own great military skill that has only grown, do indeed get on those boats to sail for Rome. The fledgling second army is routed twice by Barbarians, and retreat deeper into my territory, only to be intercepted by the rebel legions. Barbarians sack the city of Rome, then the Rebel General moves in and destroyed them all, before taking the city for himself. The remains of the Republic are occupied and annexed by the rebel legions with barely a fight after that.
Game over.