This chapter analyzes tactical intelligence, following a division by posture: offensive and mobile, and defensive or localized. There was an increase in the use of vanguards among the Greeks after the fourth century BC and among the Romans in the first. Cavalry widely used in this role. The role of reconnaissance in border security is then evaluated. It is noted that the speculatores who accompanied the legions left the field for the office sometime in the first century AD. Greek military intelligence never became professionalized, and did not ponder the sophistication of the prototypical organizations fielded by the tyrants of Cyprus and Sicily in the fourth century. Professionalism and unit identification in intelligence came neither to the poleis nor the kingdoms of Classical or Hellenistic Greece, and came finally to the Romans at least a century after they had pervaded the legions.