Uchiha Clan Massacre was one of the Darkest Phases in Naruto which changed the entire story of Naruto. So many Uchiha Clan members were killed in just one night and there was nothing done by the Elders of the Leaf Village to stop it. If there are Uchiha Clan members alongside Leaf Village in the 4th Great Ninja War then there would be not much bloodshed in the 4th Shinobi War and Shinobi Alliance would have easily defeated Madara and Obito.
So why Uchiha Clan Massacre happened and why did Leaf Village lose one of the major sources of its power willingly, Is it really good to lose every Uchiha Clan Member? let us know everything about the truth of the Uchiha Clan Massacre and whether is it really unavoidable in the Naruto series. So without any delay let us dive into it.
Uchiha Clan Massacre Origin Story
The Whole Uchiha Clan Massacre links to the start of the establishment of Clans in the Shinobi world. So let’s give a quick recap of the entire clan’s establishment story in the shinobi world. After the 3rd Great Ninja War Hashirama and Madara are the strongest Shinobi in the shinobi world and they were also Clan leaders of the strongest clans, Hashirama was the Clan leader for the Senju Clan and Madara was the clan leader for the Uchiha clan.
Leaf Village Formation

Due to Hashirama and Madara’s friendship, they too joined hands and formed a Village called Leaf Village, slowly other clans joined the village, and became a Huge village with, multiple clans. In the 1st Hokage rule, ( Hashirama Senju ) the Uchiha clan are treated the same as others and there was prosperity all over the village.
But during the 2nd Hokage rule, ( Tobirama Senju ) the Uchiha clan was forcefully moved to the outskirts of the village and they were limited to only a Police Force in the village and the Uchiha Clan also had many restrictions. These led to the Uchiha Clan’s hatred towards the rule in the leaf village.
Misunderstandings

Uchiha clan members thought that everyone was feared by their powers and they see them as threats. But actually, Tobirama moved the Uchiha clan to the outskirts of the Village because he thought the village could have a strong defense, and he assembled the Uchiha Police force because he thought it will be the strongest Army in the Leaf Village.
But due to the misunderstanding of Uchiha Clan members and Tobirama not being able to properly convey the right attitude to them. This created the flame of hatred that started in the Uchiha Clan and it is passed down to the generation and even the same treatment is given to Uchiha Clan even from the Hiruzen Sarutobi rule or we can say it is worse than the rule of Tobirama. This is the origin story of the whole Uchiha Clan hatred and the origin of the Uchiha Clan Massacre now let’s get into the actual Massacre story.
Night of the Uchiha Clan Massacre

Who Killed the Uchiha Clan?
Itachi Uchiha killed the entire Uchiha Clan in a night to save his brother and the Hidden Leaf Village. The Uchiha Clan Massacre happened before the start of Naruto. We only got to see glimpses of the Uchiha Clan Massacre in Sasuke Thoughts in Naruto and Shippuden. But the entire Uchiha Clan Massacre was shown in Episode 455 Titled “Moonlit Night ” Itachi showed Sasuke everything that happened on the night of the Uchiha Clan Massacre and why did he kill the Entire Clan and his parents.
Why was the Uchiha Clan Massacred?

Itachi Killed the entire Uchiha Clan because the Uchiha Clan members decided to make a Coup d’etat which means to overthrow the leadership in the Hidden Leaf Village. By revolting against the Elders in the Leaf Village with their Sharingan and making the Uchiha Clan free from the restrictions set by the Leaf Village Elders.
There were some discussions with the Uchiha clan by the Leaf Village Elders but there was no chance of a deal between both parties. Hiruzen ( 3rd Hokage of the Leaf Village ) ordered Shisui Uchiha to look over the plan of the Coup d’etat and ordered him to use his Mangekyo ability Kotoamatsukami to change every Uchiha mind and make them forget about Coup d’etat and to solve the issue without any bloodshed.
But Danzo one of the elders of the Leaf Village didn’t like the idea and interfered with Shisui Uchiah’s plan and took his Magekyo Sharingan making him able to execute the plan and made Shisui commit suicide and making no chance to use Kotoamatsukami or to solve the issue without any bloodshed.
Who Ordered the Uchiha Massacre?

Danzo is the head of the Anbu Black Op in Leaf Village and he ordered one of the Anbu members Itachi to kill his entire Clan. Itachi didn’t agree to the Uchiha Clan Massacre but Danzo threatened Itachi to kill his brother and made a deal with Itachi for the Uchiha Clan Massacre in exchange for sparing Sasuke’s life. Itachi agreed to it and killed all his Clan members for his village and his little brother Sasuke.
Uchiha Clan Massacre is it Unavoidable?
Uchiha Clan Massacre happened because the elders of the Leaf Village thought that if Uchiha Clan starts revolting against Leaf Village and successfully succeeded in the Coup d’etat ( To overthrow the leadership in the Hidden Leaf Village ) then the Leaf Village will be Vulnerable to the other villages and there could possibly start to a Great Ninja war.
Reason-1

No one knows about how the Coup d’etat plan going to be executed by the Uchiha Clan members and everyone knows about the potential of Fugaku Uchiha, he is known as the strongest Uchiha Clan member even stronger than all the 3 Sanin combined. So he definitely doesn’t make the Leaf village vulnerable to other villages for sure and even Fugaku wanted to take control over Leaf Village.
He could have taken the control of leaf village in no time because he had Mangekyo Sharingan and he can control 9-Tails in Naruto and go on a rampage in the village. But he never did it and even till the last he tried for a peaceful deal with the Village Elders and thought about the welfare of the village. But the Elders of the Village never really gave importance to him, even Hiruzen Sarutobi did the same.
Reason-2

Moreover, the Coup d’etat was not a sudden decision taken by the Uchiha Clan after the 9-Tails attack. It was been for years since the 2nd Hokage rule and the Elders of the Village definitely would be known about the Coup d’etat plan for many years, and they could have taken preventive measures for it and could have solved the issue long before even the 9-Tails Attack. But no Elder didn’t even thought about communicating with Uchiha Clan members.
Reason-3

Hiruzen Sarutobi never really gave much thought to the Uchiha Clan and he gave powers to other elders and Danzo to look over the issue. Even when Danzo proposed the Massacre plan Hiruzen stood Neutral and postponed the topic to talk later which made the Uchiha Clan Massacre happen.
And Hiruzen never even put a search team on the 9-Tails attack about how it happened, the Cause of the attack, the Person behind it, and other stuff. He just left the root cause and blamed the Uchiha Clan members like others. Which lead to the suspicion of the Uchiha Clan and ultimately led to Uchiha Clan Massacre.
Reason-4

We have seen in a Naruto filler episode where Minato was alive after the 9-Tails attack and was a perfect Hokage to the leaf. He made the Uchiha Coup d’etat situation under control and made peace with the Uchiha Clan Members without any bloodshed. So Hiruzen failed in being a perfect Hokage to the Hidden leaf village and even if Hiruzen Sarutobi would be half responsible as Minato, there would never be a 9-Tails attack in the Leaf Village because the Uchiha clan members would be made 9-Tails attack under control using their Sharingan powers.
Reason-5

Hiruzen gave many superior powers to the Elders and focused on relationships with other villages than solving internal problems in Leaf Village. The elders know about the Plan of Danzo and the Uchiha Clan Massacre but they didn’t even try to do anything about that and because of Danzo had full authority over the Anbu Black Ops made the Uchiha Clan Massacre happen easily. Above all Hiruzen knows about Danzo’s personality and mindset from his childhood. So why did he even give the Leaf’s strongest Army powers to Danzo knowing his evil mindset.
Conclusion
Uchiha Clan Massacre was completely avoidable the Massacre solely happened because of the incompetence and negligence of the 3rd Hokage. Hiruzen Sarutobi ( 3rd Hokage ) always neglected the internal matters of the Leaf Village. He gave more importance to building relationships with other villages than looking into the internal issues in the Leaf Village. He also gave too many powers to the Elders which made them do things like Uchiha Clan Massacre easily in a night without even knowing to him. Which makes the 3rd Hokage Hiruzen Sarutobi the root cause of the Uchiha Clan Massacre.
FAQS
Why Did Obito Massacre the Uchiha?
Itachi asked for Obito’s help in killing his whole clan in exchange for joining in the Akatsuki Organization. Obito also holds some grudge against the Hidden Leaf Village and his Clan members so he decided to help Itachi. Also, moreover, Obito agreed to this deal because he can get his hands on some of the Sharingan of the Uchiha Clan and Obito also get to join a powerful member like Itachi to the Akatsuki Organization. So Obito became a partner of Itachi in the Uchiha Clan Massacre.
How Many Uchiha Survived the Massacre?
The only Uchiha who Survived the Uchiha Clan Massacre is Sasuke because Itachi couldn’t bring himself to kill his brother. And this is the main deal between Danzo and Itachi which is to spare his brother’s life in exchange for Uchiha Clan Massacre. At the end of Naruto, the Uchiha who are alive are Itachi and Obito who Massacred the Uchiha Clan, and the survivor of the Uchiha Clan Massacre Sasuke.
Who is the last Uchiha Alive?
Sasuke was the only Uchiha alive at the end of Naruto Shippuden. Most of the Uchiha are killed in the Uchiha Clan Massacre by Itachi and Obito and those 2 were also killed in Naruto Shippuden. Itachi was killed by Sasuke in the 138th Episode Titled ” The End “, and Obito was killed by Kaguya in the 472 Episode Titled ” You Better… “. So at the end of Naruto Shippuden, the only Uchiha Alive was Sasuke Uchiha.
Did Madara know about the Uchiha Massacre?
It was never mentioned in the Naruo series whether Madara knows about the Uchiha Clan Massacre or not. But probably Madara knows about the Uchiha Clan Massacre because in the 4th Great Ninja war there wasn’t a single Uchiha against nor as an ally to the Madara so he can probably predict that there was an Uchiha Clan Massacre happened.
Or Madara could get the information from the Zetsu because Uchiha Clan is a formidable opponent to Madara if Uchiha like Fugaku Uchiha or Itachi or Shiusi is alive they could have used their abilities and gained a major advantage in the 4th Great Ninja war. So he definitely would have gotten the information about the Uchiha Clan Massacre from Zetsu or from other sources but he definitely knew about the Uchiha Clan Massacre.
How Old was Itachi, Sasuke, and Obito During the Uchiha Massacre?
Itachi was 13 when he killed his entire Clan, He graduated from the academy earlier than other Shinobi and joined the Anbu Black Ops of the Hidden leaf village. He became the Anbu Captain at the age of 11 and 2 Years after becoming captain to the Anbu Black op he killed his entire clan.
Obito Age During the Uchiha Clan Massacre
In the Naruto series, It was never mentioned the exact age of Obito during the Uchiha Clan Massacre. But with some calculations, we can crack his age Obito was 18 when he attacked the Leaf Village with 9-Tails, during the attack of 9-Tails Itachi was 4-5 years old. So when we calculate it with Itachi’s age during Massacre which is 13, We can say Obito was 26-27 years old during Uchiha Clan Massacre.
Sasuke Age During the Uchiha Clan Massacre
Sasuke was 7 years old when Uchiha Massacre happened and also at the same age he saw the death of his parents 1000s of times in Itachi Genjutsu. Sasuke experienced so much bloodshed at a very young age so it is reasonable for Sasuke to become a Rogue Ninja for more power in the Naruto series.