A destroyer could protect its force without sinking every attacker. Torpedoes threatened heavier surface ships, while gunfire could drive off enemy destroyers and torpedo boats. A fast escort could also disrupt a submarine's approach and carry the convoy or battle force beyond its useful attack area. Speed, torpedoes, guns, and anti-submarine work therefore had to fit in one ocean-going design.
Chapter · 0:52-2:20
Why destroyers need reach and speed
The opening defines a destroyer through its jobs: screening convoys, using torpedoes against heavier ships, and denying submarines a favourable attack position.