They 'swore' (an oath of) allegiance to the United States of America. [=they formally promised that they would be loyal to the United States of America]
He 'swore us to secrecy/silence'. [=he made us promise not to tell anyone his secret]
He was so disgusted by the election results that he 'swore off' politics for good.
(..) thousands of Unsullied who believe that it is. Some of you may be quick to forgive. The Ironborn are not. I swore to follow Daenerys Targaryen. You swore to follow a tyrant. She freed us from a tyrant. Cersei is gone because of her, and Jon Snow put a knife (..)2019 TvShow: Game of Thrones Title: The Iron Throne Season: 8 Episode 6