Okay, sure, in some sense it was about that, just as we can talk about the cause of the war being the laws of physics plus the entire past light-cone.

But that's not usually what we mean by "cause of war". I don't see how this is a cause in any truly useful or predictive sense. Expanding and protecting personal power certainly is necessary for wars, but it's pretty much vacuously satisfied: the prominent decision makers almost always want to expand and preserve their power. Although it often leads to wars, it often doesn't. What made or let it lead to war this time, rather than more peaceful politicking?