I just completed a Takeda campaign at the normal level, and early on in the game scored two upset victories, when I thought I didn't have a chance. Both were defending against the Hojo clan. One was defending a small knoll with 310 men to 560. I had 2
SA and 4 YS units plus 10 each YS cav. I hid the cavalry in a woods on a lark. After expending my arrows, I attacked with all units.
I had forgotten the cavalry and bang, they hit the Hojo command unit square in the rear and killed the general almost at once. I used those 10 cav unit to mop up, and got a kill ratio of 220 heads for only 36 lost and all 10 cav. survived.

The other time I was defending a bridge with only 350 men against 900 + and somehow routed them. I once again had a few YS cav. and wiped out tons of stragglers. Got 300 kills to 74 lost.

I'm not trying to brag, but thought this might stimulate some posts about your best upset victory or kill ratio in a campaign. All war stories welcome.

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Artillery adds dignity to what would otherwise be vulgar brawl.