'dux militibus imperavit ut summa virtute pugnarent.' What construction is this? Parse 'militibus' and explain why it is like this. With the same construction, rewrite this sentence using 'iubeo' instead of 'imperare'.

This is an indirect command. 'militibus' is dative masculine plural because in an indirect command, the verb 'impero, imperare, imperavi, imperatus' takes a dative subject - to order to someone to do something. 'dux milites iussit summa virtute pugnare' - with the verb 'iubeo, iubere, iussi, iussum', indirect commands follow the same construction as an indirect statement, which is the accusative plus infinitive construction. 'veto' also works in the same way for a negative indirect command.