I've been working through the achievement list to collect the campaign victory achievement for every major clan in the game.
I've successfully completed every one except Uesegi, and I'm now on my fourth attempt, and this one isn't looking too hopeful either.
The problem seems to be location related. Uesegi begin with a single province and a vassal in Northern Honshu, which is quite a distance from most of the trade nodes and surrounded by some of the most aggressive major clans. In my first three attempts I tried to complete the campaign in single player mode, which is how I did most of the others. However, even on Normal difficulty I quickly found myself cluster clucked by Takeda, Ikko Ikki, Imagawa, Hojo, and Ashina. I managed to get the Northern trade port quite easily but hardly anyone would trade with me, and despite completing the mission that provided me with a free warrior monk unit this eventually died to a man in the repeated siege assaults on my capital. My vassal didn't really help matters and just seemed to attract more enemies until it was and quickly overrun.
In an attempt to make things easier I persuaded my son to join me in a Co-Op campaign. He chose to play Takeda, and I'm having another go at Uesegi. I figured that this would at least removed one of Uesegi's traditional enemies from the mix and force Takeda and Uesegi to work as allies.
However, we are still struggling. We have managed to subjugate most of Northern Honshu, only Iwate remains free under a rebel banner but that has required major conflicts with Ashina, Morgami, Date and Honma . But beyond that we might as well be post realm divide with large enemy armies battering against our southern border provinces constantly. There are huge Oda, Chosakabe and Ito fleets off our coast preventing any chance of overseas trade and no Koku to build or defend anything.
We currently have two full Oda Armies threatening Kozuke, another large ChosaKabe Army on a fleet off Kazuza, and an Ito Army on a fleet sailing round the Noto Peninsula.
Bearing in mind that Simon and I have just completed a successful Co-Op campaign on Legendary difficulty (Shimazu/Otomo), whilst this current one is only on Normal and I am finding this quite surprising.