To order or command (typically from an authority). A formal/literary verb; modern spoken Japanese usually uses 命じる.
司令官は部隊に撤退を命ずる声明を出した。
The commander issued a statement ordering the troops to withdraw.
上司は私に調査を命ずる旨のメールを送ってきた。
My boss sent an email ordering me to carry out an investigation.
To appoint someone to a position or post (used in formal contexts).
政府は彼を大使に命ずると発表した。
The government announced that it would appoint him as ambassador.
委員長に命ずるという布告が出された。
A decree appointing him as chairperson was issued.