Naruto's premise is based on recurring wars and how they affect the lives of their victims. Though there have been numerous wars over the years, only four have been devastating enough to be labeled as Great Ninja Wars. Several shinobi were powerful enough to cause significant damage during those wars. While the first part of the series didn't focus much on the wars, Shippuden was a completely different story.
It not only emphasized wars in the backstories, but it also covered the Fourth Great Ninja War. As a result, fans learned more about the wars' history and current situation. That doesn't mean determining the strongest shinobi in each of the Great Ninja Wars is simple. There have been many legendary shinobi over the years, all of whom made significant contributions during those trying times. Investigate further to discover who the strongest shinobi was in each Great Ninja War.
Hashirama Senju and the First Great Ninja War
This was the first major conflict among the Five Great Shinobi Nations. Before the first war, the shinobi clans always fought against one another, but not on a level of a full-scale war. Hashirama and Madara worked their way to achieve peace, but at some point, the war started because of the great nations taking resources from other countries and hidden villages. During that war, all first-generation Kage and high-level shinobi participated, but none were known to be as strong as Hashirama, the first Hokage. He was the first human to be bestowed with the title "God of Shinobi."
His efforts to prevent the war were in vain, and thus, he had no choice but to participate in the war himself. No shinobi had ever been known to best him for decades. He used a unique wood-style jutsu, and he could easily restrain the nine-tailed beast by using his giant wooden jutsu. As a direct descendent of the Senju clan, Hashirama had a massive reserve of chakra, and he was exceptionally skilled at nature transformation jutsu. Sadly, at some point in the war, Hashirama died, making Tobirama the Second Hokage. Tobirama also contributed immensely to the battle and ended up sacrificing himself for the sake of his team.
Hiruzen Sarutobi and the Second Great Ninja War
Just before Tobirama sacrificed himself, he handed over the title of Hokage to Hiruzen Sarutobi. As such, Hiruzen became the leader of the village and protected it by any means possible. He was also known for leading the village for the longest period of time, directly responsible for all the decisions during both the Second and Third Great Ninja Wars. The second war started shortly after the first, leaving very little time for the shinobi nations to recover. Although Hiruzen is not that favored among fans, he was a true legend and was known to have no equal during his prime days. Just like Hashirama, Hiruzen also earned the title "God of Shinobi."
Apart from that, he was also known by the alias "Professor" for his unprecedented versatility in ninjutsu. He had advanced knowledge and skill of all techniques to have ever existed in Konoha, including the hidden and even forbidden techniques such as the "Death Reaper Seal." He was one of the rare shinobi capable of not only using but completely mastering "Nature Transformation." Hiruzen survived all three Great Ninja Wars but tragically died during his battle with Orochimaru.
Minato Namikaze and the Third Great Ninja War
The third war took place more than 10 years prior to the beginning of the series. This war was extremely brutal, forcing even children who didn't have much experience to fight. It was later revealed in the anime that Danzo was working in the shadows to orchestrate the war by having members of the Root transform into Iwa-nin and frame the village to cause war between the two Great Nations. It was during this war that Obito nearly died and gave Kakashi his Sharingan.
The infamous story of Minato single-handedly defeating over 1,000 shinobi from Iwagakure, eventually forcing a peace treaty, was one of the pivotal moments of the war. Minato's efforts during the war not only put an end to the recurring conflicts between the Great Shinobi Nations, but also earned him the title of Fourth Hokage. He earned the nickname "Yellow Flash," and until Naruto, no shinobi could match his attack speed. Minato invented "Rasengan," a technique he developed after observing the nature of the Tailed Beast Ball, in addition to his incredible speed.
Naruto Uzumaki and the Fourth Great Ninja War
The fourth war requires no introduction; it was an elaborate plot devised by Madara and Obito under the influence of Black Zetsu. In fact, the outcomes of the Third Great Ninja War were so significant that none of the Shinobi nations intended to start another war. Even the Fourth Great Ninja War began as an attempt to stop Madara and his army. The war, while tragic, was a watershed moment in which all of the Great Shinobi Nations united and declared peace on one another. This was the future that Hashirama had imagined. Nonetheless, the war was brutal, as the shinobi faced not only an entire army of White Zetsu, but also an army of reanimated shinobi, the majority of whom were dead.
Naruto was training to control Kurama's chakra when the war commenced. Although he joined in on the action much later than anticipated, his contributions were significant. On top of controlling Kurama's power, he received the chakra of all the Tailed Beasts, making him a temporary ten-tailed Jinchuriki. Furthermore, he gained sage powers from Hagoromo Otsutsuki himself. Naruto's power by the end of the war was great enough to overwhelm Madara Uchiha and even Kaguya Otsutsuki. By the end of Shippuden, Naruto became the strongest shinobi in all the great nations.