"World War I: US Navy doctrine also stated that you used your destroyer groups, when on the offensive, were to go after the enemy naval groups as a forward line ahead of the cruisers, to attack the enemy's cruiser formation, or to attack destroyers if the friendly forces were superior in number to the enemy's in that situation. Destroyers' main weapons in such a fight were torpedoes, given the fact that their guns being less potent than those on a cruiser. " Exactly what naval battle did the US fight in WWI? Yes they would always try to make torpedo attacks when possible, but that doesn't mean they were incredibly effective or a tactic that was used later. Besides, they were screening ships for the fleet, trying to weaken enemy forces. The US wasnt going to send out 5 destroyers with nothing to back them up against a cruiser. That would be suicide.
"Their PRIMARY mission was to be a screen for other, heavier ships - but they carried torpedoes to go after anything up to battleship-class vessels." Good to hear.
"Tactics for engagements would require things including salvos - which are hard to pull off with a single ship, especially given the unreliable nature of American torpedoes right up till late 1943 or so. They were used in independent strike groups, to attack other destroyers or larger ships while the main fleet either went in on another area, or were involved in other matters." Yes when destroyers were escorting something and they had no backup they made lots of suicide attacks on larger ships and a lot of the time they paid the price for it. Never though did the US navy take a group of destroyers and tell it to single handedly take on an enemy cruiser or battleship unless they had another alternative (especially since aircraft were the method of choice anyways).
"We used them that way in the Battle of Terra, where Destroyer Squadrons were used to launch attacks on the Kilrathi supercarrier Craxtha." We were also throwing out civilian craft at the kilrathi, that doesnt mean that we do this on a regular basis. If in a melee battle they see an opening, of course they are going to take it.
"Frigates and destroyers were used this way in the WC4 novel to launch attacks against the Vesuvius, IIRC." And the border worlds had lots of other ships to throw at it too?
"In End Run, the Kilrathi were using destroyers against the Tarawa as much as they were doing it against the escorts. " Kind of funny since the kilrathi light destroyer is the epitomy of the picket ship, but they never showed much in the way of brains anyways. Besides, the Tarawa isnt exactly a cruiser in terms of firepower.
If a group of destroyers were going head to head against a cruiser (or heavier) with no support at all, which do you think would win? How many battleships or cruisers have been recorded as being sunk by destroyers alone? Probably not a whole heck of a lot.