Second Shinobi World War

The Second Shinobi World War (第二次忍界大戦, Dainiji Ninkai Taisen) was the second of four great wars involving the majority of the shinobi villages and countries.

Prelude
The ended with an armistice treaty, but also left the  seriously wounded. The treaty led to a period of peace, but after about twenty years, the economic disparity between the countries had become a serious problem. The nations began to form factions, and under the pretext of expending fair rights, the countries started using military force to expand their territories. Thus, the gruesome Second Shinobi World War started.

Aftermath
As with all wars, the Second Shinobi World War brought forth many heroes and took even more lives. It was during this war that the legendary "" (伝説の三忍, Densetsu no Sannin; Literally meaning "Legendary Three Ninja") rose to fame and received their nickname from Hanzō during a skirmish with Amegakure. Tsunade in particular became famous as the world's greatest medical-nin while successfully countering all of Chiyo's poisons. It is also likely that this war was where made his name as "Konoha's White Fang" (木ノ葉の白い牙, Konoha no Shiroi Kiba).

The "Yonkō" (もちろん, Four Emperors) also rose to prominence due to their battles in the Land of Mountains. On the other side, it was the war where lost her younger brother,  and her lover,, leaving her with an extreme case of hæmophobia. It was also this war that took the lives of 's parents, an event that eventually led him to desert his village and join. The Ame Orphans lost their parents during this war, leading Jiraiya to take care of them for a while, claiming it was the least he could do. One of the orphans,, would come to desire an end to war because of his experiences from this war, a purpose he used Akatsuki for.

It was during this second war that the emerged to challenge the Five Shinobi Nations, only to be destroyed.