Why did many african leaders expect colonial rule to end after world war i?

Explanation:

This excerpt "Many of the large ships-of-war destined to visit Japan have not yet arrived in these seas, and the undersigned, as an evidence of his friendly intentions, has brought but four of the smaller ones, designing, should it become necessary, to return to Edo in the ensuing spring with a much larger force." has a purpose  to show how emphatically the american president demanded japan take part in global trade.