Navigable rivers

[silverster]

how may sea battles were done in rivers in medieval history? how many fractons (apart from Vikings) transported all their armies via river boats??

see my point?

I mean we CAN add a RIVER PORT building to increase trade (for those settlements next to a river) but i dont see a point of having an inland sea.

[Hross af Guttenburg]

There were actually a lot of naval battles in estuaires and off of major cities even in recent times: Battle of Copenhagen, Russian occupation of Stockholm harbour etc. As for the early middle ages there was a lot of activity around rivers, not just by vikings but many major crosscountry invasions were made with mahor rivers as their means of transport. Historically invasions always followed the major European rivers for this reason.