Bitcoin History Timeline
The Blocksize Wars
On August 15, 2015, well-known Bitcoin developers Mike Hearn and Gavin Andresen released an incompatible version of Bitcoin, sparking what has become known as the Blocksize Wars due to blocksize being the functional difference between this new version, dubbed Bitcoin XT, and the legacy Bitcoin algorithm.1) Many Bitcoiners were immediately worried that the proposition could damage the burgeoning Bitcoin community by splitting it in two.
https://bitcoinmagazine.com/culture/block-size-war-soldier-freedom?s=04
1)
Jonathan Bier | The Blocksize Wars, p. 1