it's pointless to compare them. When the genres were just starting out, there was barely any distinction, - people that were into extreme music listened to everything; the Norwegian scene was so militant because most of the death metal genre at the time, especially in Scandinavia, got so oversaturated that it essentially turned into heavy pop music, - musically and aesthetically; death metal there and then no longer represented any of the values it originally started with, hence the 2nd wave of Black Metal. Outside of those events, I don't see any rivalry per se, let alone a "war".