Battle for Azeroth campaign

The Battle for Azeroth campaign covers all of the overarching storylines taking place in the World of Warcraft: Battle for Azeroth expansion.

The Wound
The beginnings of the storyline actually took place during the end of World of Warcraft: Legion, after Sargeras stuck his sword in Silithus, wounding Azeroth and exposing her blood: Azerite. Both factions quickly sent a scouting force to what's left of the desert to gather samples of the material and start to realize its power.

After the launch of Battle for Azeroth, the portions of the quest chain involving Legion legendary weapons were removed, but the remainder of the storyline itself is still required.

War of the Thorns


On the surface, Sylvanas Windrunner realized that Azerite would shift the balance of power between the Alliance and Horde, and attempted to prevent Alliance forces from using Teldrassil's trading routes to ship Azerite to the Eastern Kingdoms. After skirmishes in Ashenvale and Darkshore escalated, Sylvanas ordered her forces to open fire on Teldrassil itself, which ends up burning down the tree.

This chapter was the pre-launch event and was only available in the two weeks prior to expansion launch.

Battle for Lordaeron and Heart of Azeroth
After Teldrassil burned, the Alliance immediately launched a counterattack on the Undercity, seeking to retake the Capital City for the Alliance. Anduin and Genn's forces routed the Horde defenders, captured Varok Saurfang, and confronted Sylvanas Windrunner in the throne room, but fail to capture the city as Sylvanas detonated stored Blight canisters hidden in the ceiling, covering her escape. The Alliance leadership manage to escape as well, but the city was declared lost.

Upon return from the battle, Magni Bronzebeard, the Speaker of Azeroth, reached out to the adventurer and requested some assistance in Silithus. The titanic world-soul of Azeroth had been badly wounded by the Sword of Sargeras and needs her champion's assistance to survive. She manifested the Heart of Azeroth and Magni asks the adventurer to look past the Horde – Alliance conflict and focus on what really matters.

Alas, more urgent matters arose back home, and the time had come to set out for new lands with new allies.

Kul Tiras and Zandalar
After acquiring the Heart of Azeroth, the adventurer set to the newly-accessible continents of Kul Tiras and Zandalar. The campaign's perspective split based on faction, with the Alliance focused on Kul Tiras and the Horde focused on Zandalar, each involving the traditional zone storylines. Much like in Legion, the three level-up zones per faction could be completed in any order. Once the three zone storylines were completed, a finale campaign opened up to cap off the patch 8.0 portion of the story.

War Campaign
In parallel to the level-up campaign and home-continent zone storylines, Genn Greymane and Mathias Shaw send members of their faction on excursions to the other continent, setting up camps and scouting out intel. Additional chapters were added over the course of the expansion, concluding in patch 8.2.5.

Nazjatar


Added in patch 8.2.0, Queen Azshara lured expedition fleets of the Alliance and Horde to Nazjatar, then parted the sea and dashed the ships on the newly-exposed seabed. After gaining the trust of the locals, and completing the three chapters of the storyline, a raid group of adventurers took on Queen Azshara herself in her seat of power, the Eternal Palace.

Mechagon


Also added in patch 8.2.0, a small island off the coast of Stormsong Valley was discovered, inhabited by mechagnomes. After unlocking world quests in Nazjatar, adventurers were sent to explore the area and look for new weapons in the fight against Queen Azshara.

Black Empire Campaign


Defeating Queen Azshara in the Eternal Palace set events into motion that released the seal of the old god N'Zoth. N'Zoth desired to unleash the Black Empire and take Azeroth over in its name. In addition to skirmishes in Uldum and the Vale of Eternal Blossoms, adventurers took the fight to N'Zoth directly at Ny'alotha.