Supreme Command
High Command
noun, する verb
The commander that unites the world is one with supreme command. He's better than all the other commanders who couldn't bring everyone together and now he rules over everyone.
とうすい
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
今日は学校で、天皇の統帥権について学びました。
Today at school we learned about the supreme command authority of the Emperor of Japan.