The First Shinobi World War (第一次忍界大戦, Daiichiji Ninkai Taisen), or simply the Shinobi World War (忍界大戦, Ninkai Taisen), was the first of the great wars that involved the majority of shinobi villages and countries. There are few reliable surviving records of this war, but the experiences of this war led to the birth of the tactics that still form the cornerstone of warfare. It ended with an armistice treaty, but only after all of the Five Great Nations had been seriously damaged. Even then, the peace only lasted another twenty years until the Second Shinobi World War erupted.
The war started not long after the system of one shinobi village per country was established by the founding of Konohagakure after the Warring States Period. During the war, to try and maintain a balance of power, the First Hokage divided the tailed beasts among the other five major villages when he began his peace talks with them.
The Second Hokage died during this war, while fighting against Kumogakure's Kinkaku Force, sacrificing himself as a decoy in order for his subordinates to escape. Before doing so, he selected Hiruzen Sarutobi for the position of Third Hokage.
- The conclusion of the First Shinobi World War, mirrors the events that followed the real-life First World War. World War I was ended with armistice, before a treaty was finally signed. In addition, virtually all countries on the European continent (the primary setting of the war) were completely devastated in some manner by the time hostilities ended. Nevertheless, within twenty years after the signing of the treaty, World War II would begin.