What Happens in the Fourth Shinobi World War Arcs?

The war is built in stages, and collectors of the volumes usually divide it the way the manga does: confinement of the jinchuriki, the first day's battles against reanimated squads, and the turning points as named legends return. Kabuto Yakushi, having absorbed Orochimaru's remains, sells the war its army: Edo Tensei resurrections of the Akatsuki, past Kage, the Seven Swordsmen and Asuma and Hizashi among them, forcing the alliance to fight its own dead. Naruto, hidden away for his safety, escapes confinement by mastering the Nine-Tails' chakra with Killer Bee's help and joins the field anyway.

The middle of the war belongs to Madara Uchiha, the real one, reanimated and fighting five Kage at once as a demonstration, and to the unmasking of Tobi. The masked man's identity, guessed by readers for years, is Obito Uchiha, Kakashi's supposedly dead friend, broken by Rin's death and recruited by the aged Madara. Kakashi, Naruto and Guy fight him in his own dimension and out of it, while Itachi, reanimated and free, ends the Edo Tensei by rewriting Kabuto's mind, an act that also gives Sasuke his brother's true farewell.

The final escalation stacks resurrections: Orochimaru, revived by Sasuke, brings back the four Hokage, who join the battle; Obito becomes the Ten-Tails' jinchuriki; Madara seizes that power back and casts the Infinite Tsukuyomi over the world. From inside his own plan steps Kaguya Otsutsuki, the chakra progenitor, and the last battle is fought by the re-formed Team 7 together, Kakashi included, sealing her in her own dimension as the war's true final enemy.

The war ends at the Valley of the End, where the story's two halves meet. Sasuke, intending a revolution that executes the Kage and the tailed beasts, fights Naruto in the series' longest and most symbolic duel, statue to statue, until both lose an arm and Sasuke concedes the argument he has been having since childhood. The epilogue chapters release the world from the genjutsu, free the tailed beasts, and close on the next generation.

This is nearly half the manga by volume: volumes 52 to 72. For collectors it is the stretch where edition differences matter most, because the war's length means reprintings are plentiful and early printings of key volumes, the unmasking, the Hokage reunion, the finale, are the documented targets rather than the run as a whole.