"I have found that the most critical moments in the game are when you run into another superpower faction while expanding and you're just not prepared to fight them. Especially when playing the expert setting you will find that sometimes your provinces have endured long, bloody wars with no money for buildings and your troops are plain not good enough to fight the other guy (whether from inferior armor, tech, faith, or computer advantage). This is the most dangerous part of any game, as if you have a rebellion or are invaded by another faction you can at worst lose the game and at best waste alot of time and money. A good little tactic I like to use will usually keep the other guy off balance long enough for you to make your troops more competetive: Invade any of his provinces that you can reach with one unit of light cavalry (having an expansive navy helps immensely). Mounted crossbowmen work the best, but the key is that they are FAST. Other good units include mounted archers, holibars, spanish jinettes, steppe cavalry, alan mercenary, and so on. With missileers you can harass the infantry or if he has cavalry you can get 1 or 2 good shots off before you retreat. With other cavalry you should simply retreat unless he exposes an easy unit like archers or peasants; just be sure you are always conscious of your escape route. In this way you force him to defend his provinces instead of invade yours, force him to repair his units, gain valour for your cavalry, and every so often you'll get lucky and take a province where he leaves 0 troops behind, which you can then proceed to take money from by knocking down all the buildings and retreating. Sometimes you'll get REALLY lucky and kill his king! You keep him in a quagmire at the front while you develop your rear provinces and before long you'll be built up enough to whip him like all the other factions you so easily beat early in the game." - Josh K