The ''Defiant'' makes a supply run to planet AR-558, the site of a Dominion communications relay that Starfleet captured. The relay has been under constant siege, with the crew defending it overdue to be relieved by a new crew. Sisko, Bashir, Nog, and Quark find themselves stuck on the planet and having to help hold the relay against a Jem'hadar batallion, while dealing with deadly Dominion booby-traps.

!This episode contains examples of:

* AnArmAndALeg: Nog loses a leg during a Jem'Hadar ambush.
* BattleTrophy: Reese keeps a necklace of Ketracel-White tubes hung around his neck. Episode writer Ira Steven Behr called this "about as grisly as we could get on ''Star Trek''".
* BreakTheCutie: Nog gets shot, and his leg is amputated.
* CallBack: The Starfleet and Dominion forces jam each other's sensors, just like the Klingons did in 'Nor the Battle to the Strong.'
* ConditionedToAcceptHorror: Reese.
* DarkerAndEdgier: One of the darkest episodes of the whole franchise, providing a wholesale {{Deconstruction}} of Roddenberry's vision of an ideal future humanity.
* TheDeadHaveNames: Sisko and Kira both state this at the end.
* DueToTheDead[=/=]ContinuityNod: Sisko still reads the lists of those killed in the war.
** Subverted by Vargas, who describes his dead friend as a loudmouth jerk. Though it's zigzagged as he's on the verge of tears as he does.
* AFatherToHisMen: Sisko, and he makes damned sure Quark understands that.
-->'''Sisko:''' Listen to me, Quark, because I'm only going to say this once... I care about Nog and every other soldier under my command. Understood? Every damn one of them.
* HarsherInHindsight: For all the sacrifices to defend AR-558. the Dominion will eventually retake the system in 'The Changing Face of Evil'.
* HoistByTheirOwnPetard: The Starfleeters use the Jem'Hadar's' "houdini" mines against them.
* HoldTheLine: Sisko's order to the remaining troops.
* HumansAreWarriors : Quark explains to Nog what Hew-mons are like beneath the MarySueTopia:
-->"Let me tell you something about Hew-mons, nephew. They're a wonderful, friendly people - as long as their bellies are full and their holosuites are working. But take away their creature comforts... deprive them of food, sleep, sonic showers... put their lives in jeopardy over an extended period of time... and those same friendly, intelligent, wonderful people will become as nasty and violent as the most bloodthirsty Klingon. You don't believe me? Look at those faces, look at their eyes..."
* ImADoctorNotAPlaceholder: An engineer, not a magician.
* ManlyTears: Vargas sheds them when he tells the story of his comrade, who died bandaging his arm.
* NewMeat: The relief troops at the end.
-->'''Reese:''' Children.
-->'''Sisko:''' Not for long.
* NotSoDifferent: Quark spends a lot of the episode moralizing, but in the end he drops the superior attitude, picks up a phaser, and proves that when push comes to shove he can be just as ruthless as any [[FantasticSlur hew-mon]].
* PapaWolf: Quark was quick to defend his injured nephew in the quickest and most efficient way possible: By shooting the enemy that was about to attack them.
* ParanoiaFuel: The invisible floating mines are a disturbing InUniverse example.
* RedShirtArmy: The garrison at the beacon site. Of four named troops, only Reese survives.
* ShellShockedVeteran: Everyone at AR-558 - they were supposed to be rotated out after 90 days. They've been there five months with no relief and under constant attack to the point they went from 147 troops to just 43 by the time the ''Defiant'' shows up.
* ShoutOut: The battle plays out much like the film ''{{Film/Zulu}}''. There's even a scene where Jem'Hadar are expended merely to test the defenses of the camp (of course, these Jem'Hadar were holograms).
** All of the soldiers stationed on AR-558 were named after characters or actors from the WWII movie ''Hell Is For Heroes''.
* SoldiersAtTheRear: Both engineers, Nog and the poor guy assigned to keep [=AR558=] running.
* SoundtrackDissonance: Melancholy music plays during the battle, [[WarIsHell in keeping with the episode's theme]].
** SadBattleMusic
* TragicKeepsake: Vargas's bandage, made from the uniform of a dead comrade.
* WarIsHell: This episode shows no glory, no love of battle. Just the harshness and a piece of rock which no one would care about if not for the technology put there.
* YouAreInCommandNow: Lt. Larkin was left in command at AR-558 after Captain Loomis and Commander Parker were killed prior to Sisko's arrival. He takes command as the senior officer when the ''Defiant'' is forced to retreat.
* ZergRush: The Jem'Hadar try to overwhelm the Federation garrison with sheer numbers.