This block marks the DAO fork in response to the 2016 DAO attack where an insecure DAO contract was drained of over 3.6 million ETH in a hack. The fork moved the funds from the faulty contract to a new contract with a single function: withdraw. Anyone who lost funds could withdraw 1 ETH for every 100 DAO tokens in their wallets. This course of action was voted on by the Ethereum community. Any ETH holder was able to vote via a transaction on a voting platform. The decision to fork reached over 85% of the votes. Some miners refused to fork because the DAO incident wasn't a defect in the protocol. They went on to form Ethereum Classic.