approved

After heard the preparedness of Katsura，Sakamoto went to Satsuma side for negotiation alone.
By the way Sakamoto was under the aegis of Satsuma at the time.

"Sakamoto was merely one of spy of Satsuma."
There is a theory that.

Thing that have left just as the facts of history.
Sakamoto went alone to Satsuma side.
After that Satsuma moved.
Satsuma proposed an alliance from them to Choshu.
Finally Satsuma-Choshu secret alliance was approved under presence of Sakamoto.

・・・・・・・・・

If the war began with Tokugawa.
Satsuma increase the number of troops in Kyoto and Osaka because restrain Tokugawa.

Case in advantageous of the war situation of Choshu，Satsuma propose the release of ”Enemy of Emperor” to Emperor.

Case in disadvantageous of the war situation of Choshu，also Satsuma strive  for Choshu until the end.

If did not the war with Tokugawa.
Needless to say，Satsuma propose the release of ”Enemy of Emperor” to Emperor.
　
If Tokugawa interfere it，we prepare for battle with Tokugawa in cooperation.
　
If Choshu will release of ”Enemy of Emperor”，of course we strive for Japan in cooperation.
　
・・・・・・・・・
　
After all，this alliance decided Japan's fate to the present.
Also this alliance decided Aizu's fate.
Both Satsuma and Aizu had subjected to hatred of Choshu until now.
Because give the impression of a mastermind，Choshu's hate might was strong to Satsuma than Aizu.　
However，after this，all Choshu’s hatred was directed to Aizu.