Please forgive the possibly naive nature of this question, but was it the case that all warriors were considered to be of the same kṣatriya class? Or, was it possible that the 'officers' were kṣatriyas and the 'foot soldiers' were perhaps of a different caste, i.e. enslaved śudras forced to fight? Is there any discussion of the militiary organisation according to ranks, size  and hierarchy similar to the table below? 

Thanks in advance.