On Uesugi, I am more reliant on (friendly) vassals more than ever.
Send an ashigaru unit (spearmen, to defend yourself against sudden enemy general charges) to defend the Yamanouchi when you can spare one; the purpose of this is twofold -- one is to force the battle into siege rather than autoresolve, thus favouring the defenders; the second is that you can catch routers.
Usually the main battle will be over before your reinforcements ever make it up the hill, but with each battle you can often catch 250-500 worth of enemy routers, leaving the remnants so small that many of the routing units will be destroyed when you return to the campaign map. It's very easy to get four/five unit promotions this way.
Doing this will allow the Yamanouchi to prevail against three of your likely enemies: the Takeda, Hojo and Ashina.
I would have also done this to the Jinbo (who I annexed but got swallowed up by the Hatano and the Takaoka), but I didn't reinforce them in time.
That single ashigaru unit also managed to save a second province the Yamanouchi conquered, when they lost a key battle with the Ashina, because they didn't camp in the provincial castle. Their main force retreated all the way to their capital, leaving a token force behind in the second province, which only had two archers to prevail against six (worn down) samurai archer units. The melee units fled, but my reinforcements made it up the hill (marching) and then played hide and seek with the archers. Eventually the archers routed (in my direction) and were destroyed.
[This message has been edited by Swra Latckretcnin (edited 12-20-2011 @ 06:26 PM).]