two families 'allied' [=(more commonly) 'joined'] by marriage
She's 'allied' herself 'with' the moderates on this issue.
They've 'allied with' their former enemies.
(..) I have taken stock of them. I know what to expect. And we are fully prepared. Then should you not reinstate your alliance with King Ecbert? I have no wish or need to be allied to such a degenerate monarch. Daughter, we are all aware of your immoral relationship with your father-in-law. (..)2017 TvShow: Vikings Title: The Great Army Season: 4 Episode 17