In the past week, Breitbart’s Wikipedia page has become the scene of an epic battle, with alt-right trolls descending en masse to change its content.

Breitbart News has declared war on Wikipedia, following Facebook’s introduction of a new feature that uses the free encyclopedia to combat “fake news” being spread on the social media site.

The Facebook tool, launched last week, poses arguably the greatest test in years to the volunteer-run online encyclopedia, constituting a massive threat to the internet’s largest and ostensibly most trusted source of free knowledge.

The tool allows users to see information on publishers. This information is aggregated from Wikipedia, which is itself edited by millions of users.

When Breitbart discovered that, according to Wikipedia editors, people should treat its content with a grain of salt – describing the site as “intentionally misleading” – the response from the white nationalist alt-right movement’s self-proclaimed platform was fierce and quick. And its actions have wreaked havoc on Wikipedia.