Why river warfare disappears from many Second World War accounts

Was riverine warfare absent from the Second World War, or is it simply under-discussed?

It is under-discussed; the Soviet Navy, among others, operated many vessels for river warfare.

Riverine warfare was present in the Second World War, particularly through the Soviet Navy's many vessels used on rivers. This is a signpost rather than a catalogue of flotillas or campaigns. It widens the geographical frame beyond oceans and reminds readers that naval organisations also fought on inland waterways.