Madara Uchiha is the only shinobi who could go on par with Hashirama Senju. His battle prowess made him the most feared shinobi of all time. Apart from his battle prowess, his intellect is second to none. He planned his rebirth and made sure nothing went out of plan. For that, he sacrificed countless lives.
Even though Hashirama Senju defeated him twice, after his reincarnation, Madara Uchiha became a completely different person. He defeated Hashirama Senju, and there was not a shinobi who could even touch him. But he did all these while barely using the Mangekyo Sharingan. It led to a popular fan theory that the Ghost of Uchiha had some sort of time travel to correct his mistakes on the battlefield.
Madara Uchiha Is a Time Traveller
During the Fourth Great Ninja War, Madara had implanted Hashirama cells into his body and could use Wood Style Release. It greatly boosted his powers. In flashbacks, it was seen that due to using his Mangekyo Sharingan extensively, he lost sight and transplanted his dead brother’s eyes to unlock the Eternal Mangekyo Sharingan. But he was barely seen to use such an overpowered technique during the war.
Madara Makes Mistakes – A Naruto Theory
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He took on the whole platoon of shinobi and yet came out unscathed. He crushed them and destroyed their morale. Given Madara Uchiha is an exceptional shinobi it is hard to believe that no one landed a single blow on him. Thousands of shinobi were attacking him at once, and one could have landed a lucky shot, but they did not. On the other hand, he took on all the Five Kage and left them on the verge of death.
The Naruto Storm Generations OVA featured a fight between Hashirama Senju and Madara Uchiha. During that fight, Madara lost footing while blocking a shuriken but rewind time to rectify himself. He did it using his Mangekyo Sharingan. Even though it was non-canon, it gave the fans an idea about the extent of his visual prowess. He might have used the same technique during the Fourth Great Ninja War too.
No one is perfect, not even Madara Uchiha. He might have made mistakes and miscalculations during the war, but he immediately rectified himself using his secret Mangekyo Sharingan power. It might seem like he barely used his Sharingan, but in reality, he was using it every once in a while. Moreover, being reincarnated, he had unlimited chakra, which helped him land a crushing defeat on the entire fleet of shinobi. Not even the Five Kage could land a single blow on him.
Boruto Introduced the Concept of Time Travelling
In Boruto: Naruto Next Generations, Sasuke Uchiha and Boruto Uzumaki were seen to time travel to the past to save Naruto from Urashiki Otsutsuki. It introduced the concept of time travel in the Naruto franchise. Moreover, Madara is a genius, and it does not come as a surprise if he could do something so wicked. More than winning, he wants to crush the morale of his enemies.
During the war, he could have finished the platoon with one meteor but summoned another just to show them the difference in power and crush their morale. Madara Uchiha always knows from what direction blows are coming and is never left in a state of surprise. Rewinding time seems to be the only legitimate answer to this awesome power.
Thanks to it, he always came out on top and continued his reign of terror. But it is still just a theory. There is no mention of him using time travel during the war. Even though it is a theory, it is pretty interesting. But until official confirmation, it will always remain a great fan theory.