Battle of Canary Wharf

The Battle of Canary Wharf was one of the most major battles between Humans and aliens in history.

Background
The Battle of Canary Wharf has its roots in the Cult of Skaro's and the Genesis Ark's escape into the Void from the Time War, causing a crack in the universe, allowing travel from one dimension to the next. (DW: Doomsday)

Progress
From the crack in the universe, the Parallel Earth Cybermen were able to travel from their dimension into ours, and infiltrated the planet in the disguise as deceased Humans coming back from the dead (ghosts). (DW: Army of Ghosts)

The Cybermen suddenly appeareed in their true form, breaking into houses and promising to upgrade all Humans, commanded by the new Cyber-controller. (DW: Army of Ghosts, Doomsday)

Simaltaneously, the Daleks had exited the Void Ship, extracted information from a member of staff from Torchwood 1, and proceeded to communicate with the Cybermen via Dalek Thay and declare war (or in Dalek Sec's words, "pest control").

After a quick fight (Humans & Cybermen vs. Daleks), the Cult of Skaro travelled to the main room in Torchwood Tower (Canary Wharf), elevated outside above the roof, and opened the Genesis Ark, releasing millions of Daleks who, under Sec's command, proceeded to "exterminate all life-forms below", killing Human and Cyberman alike.

Eventually, the Tenth Doctor and Rose Tyler opened the Void, sucking all the Daleks and Cybermen who had been in the Void back into it, and finally sucking Rose herself in to the Parallel Earth where her parents (Pete Tyler and Jackie Tyler), and her boyfriend (Mickey Smith) were. (DW: Doomsday)

Aftermath
After the battle, the governments of the Earth denied it ever happened and blamed it on mass hallucination caused by terrorists polluting the water supply with psychotropic drugs. (TW: Everything Changes)