How decisive were missile weapons in battle?

[fiatjustitia]

I infer from inscriptions and early writings that their effectiveness waxed and waned. In early antiquity they seemed to be an important arm- witness the stone carvings of the Persians, Egyptions and Hittites. Yet by the time of early and middle antiquity my sense is that they were relegated to a secondary role. However by late antiquity historians again seem to imply that they were decisive. Was this due to changes in tactics, or changes in defensive or offensive technology? I honestly cant make up my mind.

title edited by moderator due to spelling mistake