25 December 1859,
In Australia, 24 European rabbits were released, starting one of the fastest colonizations in history. They were commissioned by colono Thomas Austin for the hunting sport. Without counterbalance, this species spread 100 kilometres a year westward, becoming an uncontrollable pest for flora and fauna. It was the fastest colonization ever done by a mammal species, and for 50 years it spread across the island. It is taken as an example of factors that can lead a system to collapse.
Source:
Nagore Irazustabarrena Uranga, Two dozen rabbits to destroy Australia (ARGIA, September 29, 2019).