Hoo boy, that’s kind of a can of worms I’m not sure you want to open, because it’ll play merry hell with the timeline.
See, all of GRRM’s wars are very short: the Conquest was one year, the Dance was three, First Blackfyre was one, Ninepenny Kings was one, Robert’s Rebellion was one year but across two, Greyjoy Rebellion was one, and the War of Five Kings is three and counting.
But to give a few examples from medieval warfare:
- FIrst Crusade (4 years)
- Second Crusade (3 years)
- Third Crusade (5 years)
- First War of Scottish Independence (32 years)
- Hundred Years’ War (115 years)
- Wars of the Roses (30 years)
And that’s just a handful of cases, you can find many many more.
So GRRM’s longest wars are Medieval history’s shorter wars.