In 2015, Andresen and Hearn began pushing Bitcoin XT (BIP101) which was intended to change consensus rules and increase Bitcoin’s block size. They originally attempted to get BIP101 merged into Bitcoin Core, and said it would only go in if the other developers agreed. They never reached that agreement. The fight was over how much of an increase there should be and how fast it needed to come. But mostly it was over whether forcing a contentious hard-fork was legitimate at all. A contentious hard-fork either breaks the chain in two or forces some to swallow rules they never agreed to. Sipa, quoting someone from the debate: "I did not sign up to be part of a central banker's committee." And so when they couldn't convince Core devs, Andresen and Hearn went directly to mining pools and misrepresented Bitcoin XT as an upgrade to Bitcoin Core. I know this firsthand because I was running BTCC Pool at the time and took the call with them. They also set activation of BIP101 at just 75% miner signaling. That's below the 95% that normally locks in a Bitcoin consensus change. This was the starting point of the Blocksize War which lasted over two years. History rhymes.