The war arc is a story arc that concerns two or more large-scale factions(City-sized at least) in conflict with one another, with the protagonists being involved somehow.
The scale will usually be very epic, with politics usually playing a role.
Expect to see a Big Badass Battle Sequence
Anime and Manga
- The Whitebeard War saga in One Piece
- The Shinobi World War Arc in Naruto
- Bleach: The war between the Soul Society and Lord Aizen's Arrancar.
- The Arachnophobia arc in Soul Eater.
- The Green Lantern has the Sinestro Corps War (Green Lantern Corps vs Sinestro Corps), War Of Light (7 different Corps against each other) and Blackest Night (everybody against Black Lantern Corps)
- Chaos War is this for Incredible Hercules
- Cosmic Marvel has multiple war arcs in last few years. Annihilation is war between Negative Zone and Universe, Annihilation Conquest is Phalanx Invasion on Kree Empire, War of Kings is war between Kree nad Shi'Ar empires and Thanos Imperative is war between The Universe and Cancerverse.
- Books 21-25 (and beyond?) of the Gor series are focused on the war between the city-state of Ar and Cos, the island Ubarate. Tarl, our protagonist, is on the side of Ar; but Cos won the war...so far.
- Mercedes Lackey has The Mage War in her Valdemar books.
- Two Star Trek series did this and one would have, if not for Executive Meddling.
- Season 3 of Star Trek: Enterprise has the Enterprise racing to stop an attack on Earth.
- Deep Space Nine had the Federation at war with the Dominion.
- The Star Trek: Voyager writers wanted to make "Year of Hell" a season-long arc, but the executives said no, and it was instead made into a two-parter.
- Deep Space Nine actually had two war arcs: The Dominion War, and the war between the Federation and the Klingon Empire (before both sides discovered they'd been played like cheap fiddles)