The time for any nation to create war will be over natural resources that are depleting globally.
That is the conventional wisdom. However, we are discovering resources at a vastly more rapid rate than we are depleting them - including oil - so such a war is unlikely. At least in the next few centuries it is unlikely.
Vastly more rapid rate than we are depleting them?
I get tired of quoting the worn out statistic that we are consuming the world's oil deposits at a rate one million times greater than they were generated by nature in the first place.
Whether you're talking oil, coal, shale gas or methane hydrate extraction, or even access to fresh water, minerals, agriculturally productive land etc, the problem remains the same
TOO MANY PEOPLE=TOO MUCH CONSUMPTION because there are TOO FEW RESOURCES.
Imho we (in the west at least, and certainly in densely populated places like Europe and Japan) have seen our high water mark. The wars you speak of are already happening - they have locally happened in the past (Easter island, the Mayas, lol, even cowboys, farmers and indians - need I mention Lebensraum?). In a globalised economic world, a global resource war will ultimately be inevitable. Just hope you won't see it.
As usual there will be a few winners and loads of losers - and the 'side' you are on doesn't define which of those you might be.