Undead lieutenant

You attempt to empower an intelligent undead (Intelligence 5 or greater) with the ability to command other undead in your control. The target must make a Wisdom saving throw if it is unwilling.On a failure the spell takes effect Other undead under your control obey the subject intelligent
undead as if it were you. You may still give orders to the
undead normally, superseding the orders of the subject of the spell. Once the spell ends, the intelligent undead is aware that it has been used in this way.

At higher Levels.When you cast this spell using a spell slot of 4th level or higher, the maximum duration for this spell
Increases by 10 minutes for each slot level above 3rd.