Gad, it must have given you an adrenalin rush! Shinano has always been my favourite province, especially when it comes to defence. I usually have 5 archers and a couple of monks hidden in the jungles, plus some yari cavalry and ashigaru/samurai in the middle. If you use the terrain to your benefit, your archers can simply wreak havoc on the troops below, even when your are outnumbered.

I encountered the same situation (re morale) as yours while playing yesteday. I rushed my daimyo (mori motonari) across the bridge because the enemy cavalry archers refused to budge within range of my samurai archers...He probably hacked 15 of 'em down before I lead him to the edge of the river. The fools tried to follow him (but at this time they' d alreadyt stopped firing) and came within range of my own archers. All in all, 10 died (his hotomachis). He was a level 6 general - Can't believed he made the river crossing by himself! And never once did he waver....what a thrill..

Oh yeah..the computer is pretty smart when it comes to choosing/breaking alliances with you. They will choose whatever that is beneficial to them (kudos to the AI for making it more human). Once I declared war on the shimazu (while playing mori)..the shimazu sent me a message saying they'd broken their alliance with the IMAGAWA...and helped me attack their provinces. Ain't that a shot in the arm?

I repaid them by invading their provinces couple of seasons later..hehe