zapovedati

1. (+ dat.) to order; to command
   Ne možeš ti meni da zapovedaš! — You can't order me around!
   Oficir je zapovedao vojnicima da čekaju. — The officer was ordering the soldiers to wait.
2. (+ instr.) to be in command of
   On je godinama zapovedao tim brodom. — He was in command of that ship for years.

The person ordered is in the dative (zapovedati nekome); what one commands is in the instrumental (zapovedati vojskom).