To annex (an inferior state) to a better state as a means of allowing the ruler regarding the reduced state to retain name and limited authority.
resulting in to act through an agent or even to hold a subordinate position; to annex; -- specifically placed on the annexation during former German kingdom of a smaller German state to a bigger, while enabling it a nominal sovereignty, and its particular prince their ranking.
To annex a country while allowing the ruler associated with country to hold particular rights
is mediatized because of the Roman Empire
to create mediate; decrease from an immediate or direct to a mediate or indirect relation through interposition of a secondary superior or managing agency.