You people are thinking too 2-dimentional, Thermopylae could be done as a planetary defense scenario. A small group of ships need to prevent the invasion of, lets say Setlik, from an invasion force until reinforcements can arrive from Bajor.
Defending Forces: No more than 6 Federation/Klingon ships. Heavy Frigates being the largest.
Attacking Forces: At least twice as many light attack ships with an equal number of troop transports.
Phoenix...
"I'm not saying there should be capital punishment for stupidity,
but maybe we should just remove all the safety lables and let nature take it's course"
"A Place For Everything & Nothing In It's Place"