Testifying in a courtroom, Superman tells one of the magistrates that he doesn't understand what he's saying, as the other accused Leaguers and a large audience look on. The Tribune angrily responds before being interrupted by a colleague who points to a device on their desk. The Tribune hits the device, and it begins translating his Interlac speech. Superman declares (not for the first time) that the League did not intend the harm they caused, but the prosecutor finds that hard to believe, going into a long list of the damage, direct and indirect, done by the Leaguers.
A pair of observing Kroloteans discuss the trial; one is shocked to learn the "savages" have refused to bribe the court. When the prosecutor asks Superman why they were put under Vandal Savage's control, Superman is forced to admit that the reason is unclear. The testimony is interrupted by a commotion from the audience when a series of holographic screens pop up carrying news of the Reach's arrival on Earth. One of the Kroloteans is happy to see Earth finally being controlled, but his companion is more concerned about the Reach's growing influence in the galaxy.
The Tribune attempts to restore order, as Martian Manhunter and John Stewarttelepathically discuss the Reach. John reveals that the Reach were conquerors millennia ago; it took the entire Green Lantern Corps to stop them, leading to a treaty signed with the Guardians of the Universe stating that the Reach could only claim a world to which they had been invited, and that no Lantern may ever return to such a world. As the Tribune finally manages to quiet the crowd, in the shadowed back row Vandal Savage comments to the alien next to him that the Reach having access to Earth's meta-population could have long term implications about who will rule the galaxy. The alien rises, stepping down to the courtroom aisle, shocking the crowd into silence, before wordlessly leaving the room.
The Reach have also detected the object. Agitated, the ambassador wonders why "he" would come, and hails him, claiming Earth as Reach property and demanding that he reverse course. The occupant of the approaching object denies the request, explaining that he came because the Reach is there. The ambassador closes the channel and turns to Black Beetle for the appropriate response, but there was none forthcoming.
At the partially-repaired STAR Labs, Green Beetle briefs Captain Atom, Nightwing and Adam Strange on the approaching threat, claiming to have his scarab access the Reach's database. He explains the approaching object is the Warworld, a massive artificial satellite. Created by a now-extinct race, the Warworld is a doomsday weapon capable of destroying whole planets. It was reactivated by a once-lost crystal key, somehow found by the current commander, Mongul. Now at the helm of the Warworld, Mongul is able to control it through thought alone. Beetle also tells them that Mongul was once sole dictator of his homeworld, but was ousted by another. He plans to retake his homeworld by first taking over the whole galaxy. Beetle surmises that Mongul must see Earth as a threat to that plan.
Mal and Karen walk the university grounds. Mal is happy to finally spend some time with his girlfriend, but Karen is distracted—she has spotted the Warworld in the sky next to the Moon.
On a GBS news broadcast, Cat Grant describes the panic at the arrival of the "encroaching planetary body", which has already begun to have a gravitational impact. Images of Aquaman and Red Tornado rescuing civilians are shown as she describes changes to the tides and the occurrences of mini-tidal waves.
At the United Nations building, the ambassador and Secretary Tseng conduct a press conference. The ambassador announces that even though the Reach have only a single, unarmed ship, they will stand by Earth's side in the face of the threat.
Mongul points out that the Earth under Reach control is too big a threat to his plans, and so must be destroyed. He also tells them they would be grateful for their destruction if they knew what was coming with the Reach. Mongul activates the Warworld's main weapon; a segment of the Warworld's surface retracts, revealing a huge laser emitter. The laser powers up and fires, but as it does, Doctor Fate emerges from a portal in Earth orbit and conjures a giant magical portal, which absorbs and reflects the laser, destroying the emitter. Angered, Mongul targets Fate with a number of missiles. The missiles detonate, but fail to harm Fate, who is protected by Rocket's force bubble. Captain Atom, Captain Marvel and Green Beetle emerge from Fate's portal and assault the Warworld, as many small energy weapons from across the Warworld's surface open fire. Captain Atom reports their status to Nightwing on the Watchtower—though not really doing much damage, they have Mongul's attention. Nightwing is pleased, and tells him that the Team is already on board, as the Team members deploy in a chamber on the Warworld.
Aquaman asks Nightwing if the Team have been detected. Nightwing explains that Blue Beetle was able to bypass the Warworld's security systems. Superboy reports that Alpha Squad—Wonder Girl, Arsenal, Wolf and himself—are en route to attack Mongul. Blue Beetle reports for Beta Squad—Beetle, Beast Boy and Impulse—who are en route to the crystal key chamber. Bumblebee reports for Gamma Squad—herself, Guardian and the Super-Cycle—who are moving towards the power core. The three-pronged assault, devised with navigational input from Green Beetle, would succeed if any of the squads accomplish their objectives. Batgirl reports that Delta Squad—Robin and herself aboard the camouflagedBio-Ship—are laying down cover fire for the League members.
Aboard the Reach vessel in New York, the ambassador comments on how odd it is for them to be rooting for the champions of Earth, as they watch Blue Beetle's visual on a monitor.
In a Warworld corridor, Beta find themselves with nowhere to hide as a carriage arrives deploying a number of battle drones. The trio engage the drones, as Beetle reports that they have been spotted. Guardian, already under fire with the rest of Gamma, declares he likes the attention—the Warworld has taken better notice of him than his girlfriend. Bumblebee is surprised at the slam at her expense while on a mission, prompting Mal to angrily ask when she isn't in the middle of a mission.
Meanwhile, Alpha is also battling drones. Superboy is not happy when Arsenal takes out a group with his rocket launcher without warning him. Arsenal is unrepentant, and Superboy urges them to move on—they are close to Mongul. The quartet enter the command center and face Mongul. Arsenal comments on the invader's great size, but Mongul is not so impressed by the Team. They attack him, but Mongul easily swats aside Superboy, Wonder Girl and Wolf, and is unharmed by Arsenal's rocket. Superboy appears out of the smoke to punch Mongul in the face, to little effect. Mongul picks up Superboy, and noting the symbol on his shirt, asks the Kryptonian if he, so proud of his powers, believes that his world was the only one with a red sun. Wonder Girl lassos Mongul, who easily pulls her in to knock her out with one blow. Arsenal hits him with a foam bolt, but Mongul quickly slams Superboy to the ground and frees himself. Wolf then attacks, but Mongul, through playing games, throws him onto Wonder Girl. Arsenal fires a knock-out gas bolt, but it is ineffective. Mongul charges at Roy, but is intercepted by Superboy. The delay is only momentary as Mongul slams Conner's abdomen against his knee. He once again focuses on Arsenal, blocking the barrel of Roy's rocket launcher with his hand, and causing it to backfire. With all his opponents incapacitated, Mongul tries to explain the mercy he offered by trying to end their world quickly. Instead he must now do it the hard way, unleashing a vast swarm of missiles.
On GBS, Cat Grant reports that the Earth's military leaders are mobilizing all air defenses against the assault. She passes on Homeland Security's recommendation to stay at home, rather than attempt evacuation—there is nowhere to go.
In Earth orbit, Doctor Fate conjures an enormous protective shield, as the other Leaguers destroy as many missiles as they can. Batgirl informs the Watchtower that the Bio-Ship estimates that their efforts will take out 64% of the missile strike. Aboard the Watchtower, Aquaman says their systems estimate Earth's military will neutralize a further 13%. On the Reach ship in New York, the scientist reports that 23% of the barrage will be enough to destroy a hemisphere and spoil all of Earth's "meat". The ambassador orders that the Reach's fleet be mobilized in order to protect their investment.
A number of Reach vessels emerge from the waters and head into space. They open fire on the Warworld's missiles, but many of the ships were destroyed in turn. In New York, the scientist reports that the Earth was safe for now, but two-thirds of their fleet has been destroyed.
Back aboard the Warworld, Gamma reaches the power core. Guardian and Bumblebee enter the chamber, while the Super-Cycle holds off the battle drones, prompting Mal to remark that he loves a lady he can count on. Bumblebee tells Mal she gets his message and that he should stop pouting. He angrily retorts that he isn't pouting and says she should hurry and blow up the core so they can go. Bumblebee explains that they can't simply destroy the core, they must disable it, making Mal feel belittled. Bumblebee tries to smooth things over before giving up in frustration and entering the core. Mal quietly wishes her luck.
Meanwhile, Beta battles their way into the key chamber. As Blue Beetle reports sighting the crystal to Watchtower (and the Reach observe his viewpoint from their ship), a horde of battle drones arrive.
At the power core chamber, some drones begin to break past the Super-Cycle. Bumblebee's attempts to disable to core by targeting certain circuits with her stings are thwarted; she tells Guardian the power keeps being rerouted. Mal tells her to reroute it somewhere useful. Bumblebee calls him a genius, and targets a new set of circuits.
At the command center, Alpha begins to wake up. Mongul calls in battle drones to deal with them, but as they arrive, Bumblebee completes her plan and a power surge overloads Mongul's control device. Mongul is dazed, and the battle drones clatter to the ground. Sensing an opportunity, Superboy calls for an all-out assault on the dazed despot. They successfully knock him out, and Wonder Girl moves in to restrain him with her lasso.
On the Warworld's surface, missiles about to launch stop in their silos. Superboy confirms to Captain Atom that Mongul is down. Batgirl congratulates him, but he demurs, saying someone else did it. Meanwhile, battle drones in the power chamber deactivate as Bumblebee emerges from the core, grows to full size and embraces Guardian.
In the key room, Beetle takes the crystal key for safe keeping. As he does so, the Warworld's weapons port closes back up. Watching from the Reach ship, the ambassador notes that though they have paid a price, he believes they acquired value in return. On the Watchtower, Nightwing congratulates the Team, and tells them to gather together so they can come home.
Beta and Gamma meet at the entry point, shortly joined by Delta. The Teammates celebrate their victory, as they wait for Alpha, who are having problems carrying the hefty Mongul. Guardian congratulates Bumblebee; though they all helped, it was she who saved the day. Bumblebee reminds him it was his idea, but he tells her she would have come up with something without him, that she is destined for great things and that she has outgrown him. She tells him that he is an idiot after all, and that she is too, since she kept taking him for granted. They kiss, but are interrupted by Arsenal, who asks how he can receive the same reward. Wonder Girl answers him with a kiss on the cheek. With the whole Team gathered, Blue Beetle hits Impulse on the back of his head with the crystal key, and fires his sonic cannon, knocking out Batgirl, Beast Boy and Guardian. He then charges Superboy, sending him clear across the hanger and pins Wonder Girl to the ground with Mongul and staples. Arsenal, terrified at the thought of being captured again, opens the entry hatch. Sphere is sucked into space before Blue Beetle is able to close the hatch. He takes advantage of the chaos to blast Robin, Bumblebee and Wolf with his sonic cannon. Arsenal uses a rebreather to help with the thin atmosphere and moves to escape. Beetle tries to staple him, but Superboy takes the hit, allowing Arsenal to get away. Beetle knocks Superboy out, then ensures the crystal key is still in his possession. Observing through Blue Beetle's eyes, the ambassador reaffirms that they have acquired value.
The title refers to the Warworld, the giant satellite that Mongul controls. His threats to Earth could be considered an act of war, which result in the Justice League, the Team, the world's military forces and even the Reach responding. It may also imply that events are now leading to a war with the Reach, given that Blue Beetle has revealed himself to the Team as a Reach operative and taken the key from Warworld, and the Reach revealed a hidden fleet on Earth while claiming they only brought one weaponless ship "for peace".
Blue Beetle openly betrays the Team as an agent of the Reach. He was secretly turned by Green Beetle in "The Fix", and unwittingly revealed this to the abductees in "Runaways".
Arsenal has a panic attack at the thought of being captured again, referencing to his abduction by the Light before the events of the series. It was not until "Bloodlines" that he was freed.
"War" garnered an average of 1,987 million viewers.
There is a time jump of one month and 21 days between the first two timestamps, making it the second biggest time jump within an episode, with the first being "Happy New Year" with its five-year time jump.
Mongul's recurring invoking of his mercy is a reference to one of Mongul's weapons of choice in the comics, the Black Mercy.
Producer Brandon Vietti revealed that "War" was one of the first stories planned for Young Justice, as early on they needed to figure out how to make the adventures of a team of sidekicks more important and interesting than those of the Justice League. Thus, they came up with the scenario of the Warworld attacking: while the League defended Earth from the attack, the teenage covert ops team would sneak in and shut the Warworld down. This helped establish the dynamic of the show. Knowing it would take time to build up to that scenario, the story was put to one side (as a 3x5" card bearing the words "War World") until it was picked up for season two.
This episode loosely adapts the events of DC Comics Presents #28 (pre-Crisis continuity). Mongul, who was mentally controlling Warworld's systems from the control chair, faced off against Superman and Supergirl. The pair drew fire and taxed the control system so heavily that Mongul was knocked unconscious.
Who was the other tyrant that ousted Mongul from his dictatorship on his planet?
Blue Beetle:(over the radio)The Warworld knows we're here. Guardian: Fine by me. I like the attention. At least a big alien death moon notices when I'm around. Bumblebee: Was that a slam... on me?! In the middle of a mission? Guardian: Woman, when are you not in the middle of a mission?!