gain dominion over (someone or something)
To be in a position of power over someone or something. Good luck gaining dominion over this department—everyone here is loyal to Helen. They really went to war just to gain dominion over that tiny island?
gain dominion over someone or something
to achieve total authority over someone or something. The dictator sought to gain dominion over the entire country. Harry was not happy until he had gained dominion over the people who worked for him.