- You see; Like I've said many times,.. Madara knew that Yondaime wasn't easy to capture. So his plans was messing the bond between Konoha and Uchiha, for letting the top tier of Konoha think that the Uchiha's were behind the attack. Madara knew that lots of people wouldn't believe that it was MADARA that made that attack ( except Yondaime, Jiraiya ).. but other sharingan users. The massacre was needed so he could get his revenge on his clan, simple because;
- his clan turned him down when they choose Hashirama as their leader
- the sacrifice of his little brother was for nothing
- and let us not forget; Madara just didn't like 1st Hokage and he wanted to be the LEADER. Madara Uchiha is the real core of Hatred among the shinobi's.
So by creating chaos in Konoha, other countries would surely take that as an opportunity to attack. It would have triggered a fourth ninja war and many innocent people with no ties to the ninja world, would die all for the sake of Uchiha's clan self- interest. That was his MAIN REASON. Creating Intern Extern problems for Konoha; making them vulnerable from the inside as well from the outside.
Madara Uchiha has everything planned out from the beginning. He knows how the system work between the nations, the political reasons and the greed between the countries. Madara needs sasuke for many reasons.. Itachi Uchiha was someone that Madara couldn't manipulate at all. Itachi was for sure at the same leaque as him, if it comes to intelligence. Madara couldn't play his mind and thats why he has been waiting all those time for his death. Both of them had their own plan and for getting that executed; they coudn't take the risk of fighting eachother ( Thats something I assume ) because if they fought eachother, they would both lower their risk for getting their plan executed with succes.
- Madara's world domination etc..
- Itachi's plan for Sasuke, Naruto etc..
And what I've written below is one of the reasons why the Kyuubi is Uchiha's pet:
The reason why the kyuubi matches to be an " Uchiha pet " , is because the HATRED LEVEL of the Uchiha's are match- on with the Kyuubi's inner personality; and that is simple destroy everyone that strives for peace and love. Kyuubi is exact like Madara in his catogory; Kyuubi being the most evil one among the Bijuu's, Madara being the most evil one among the Shinobi's + they both have a huge capacity of chakra.. it's a hard thing to deal with; Maximum Hatred and Chakra.