The prime cause of WW1 was unresolved issues involving several large empires (France, Britain and Russia) and the new "upstart" one, Germany, who found that there was no room in Europe for another empire. Germany, so newly unified, believed that the big boys were ganging up on Germany and squeezing her attempts to fulfil what Germany believed was her right: an empire of her own.
Germany saw the British as reactionary: as did Napoleon in his time, and with good reason. Germany had never forgiven France for what Napoleon did in Germany, and this, also, led to waves of embracing then rejecting Liberal ideas. This led to nationalism, Pan Germanism and, ultimately, the Nazis. The Tripartite pact between the 3 big empires was further compounded by often ancient principles, such as the (largely defunct) Holy Roman Empire (which had been Germanic since Charlemagne), and also the Ottoman's long standing reactions against the Big 3 empires, also for historical reasons.
Germany felt that she was being deprived of her rightful place in the world: the big 3 empires, plainly, felt that there was no more room for another empire in the world. Ironically, the bloodshed of WW1 would do nothing to resolve that.