The Gordon Riots of 1780 begin as an anti-Catholic protest in London against the Papists Act of 1778, which had been intended to reduce official discrimination against British Catholics.

The protest evolves into riots and looting.

The Popery Act 1698 had imposed a number of penalties and disabilities on Roman Catholics in England; the 1778 Act had eliminated some of these.

An initial peaceful protest leads on to widespread rioting and looting and is the most destructive in the history of London.

Painted on the wall of Newgate prison is the proclamation that the inmates have been freed by the authority of "His Majesty, King Mob".

The term "King Mob" will afterward denoted an unruly and fearsome proletariat.

The Riots come at the height of the American War of Independence, when Britain is fighting American rebels, France, Spain and the Dutch Republic.

They lead to unfounded fears that the riots had been a deliberate attempt by France and Spain to destabilize Britain before an imminent invasion similar to the Armada of 1779.