About that, I don't really see how us stockpiling weapons that we will likely never use as much different than paying for half a million soldiers in a standing army during, say, a two century period of peace. It's something of a modern (read: capitalistic) perspective that "if you build it, they will come" when it comes to creating war machines, when, in reality, the skirmishes themselves tend to be generated as normal part of human interaction. What tends to cloud that perspective is the means by which catastrophic failure is administered. Today, its the the threat of a nuclear holocaust; in the 2nd Century BCE, it was a massive barbarian coalition - in either case, panics are/were generally an opportunity for over zealous military commanders to build a complex that fortified the martial industries.
At the turn of the 20th Century, there was a unique situation that actually contributed more to the worldwide nature of the conflict more than the fruits of the Industrial Revolution. In particular, the fact that most of the industrialized countries drawn in to World War I were colonial powers tended to extend the theater of the conflict across continental boundaries. If it wasn't a direct conflict between colonies with competing masters, it was the influence of European combatants on neutral countries on other continents due to trade (which became global because of colonial expansion). Much is made of the new, deadly machines introduced and refined for this global conflict (tanks, portable automatic firearms, chemical warfare, and, to a limited extent, combat aircraft), yet it was the fact that the battles involved so many intercontinental players that contributed the most to the deadly results of these conflicts. Furthermore, World War II would not have happened if these same global conflicts had been properly resolved prior to the rise of Hitler.
That being said, we have a long memory when it comes to war. Just about everyone living today was born after the collapse of the colonial system, and that tends to color our perspective when it comes to the nature of conflict. We still see war as being a global event even though it always has been a series of perpetual small scale skirmishes. Intrinsically, conflict has always been a general-use balance between marginalized groups and society as a whole, so it should be no surprise that conflicts continue to happen even though we're supposedly in a time when the fear of global war haunts us into believing that war of any type can't ever happen again.