“Who ended slavery? The United States.”
The USA was a latecomer to abolition.
Pardon the citation from Rooters but they do have a good article on the topic:
https://www.reuters.com/article/uk-slavery/chronology-who-banned-slavery-when-idUSL1561464920070322
Who started it????
https://www.thoughtco.com/the-role-of-islam-in-african-slavery-44532
Later they moved on to capturing and enslaving Europeans and then Americans by attacking their ships.
The Marine hymn has “from the shores of Tripoli”. It is there for a good reason.