The Bitcoin Cash community experienced one of its most turbulent episodes in November 2018 when two competing implementations—Bitcoin Cash ABC and Bitcoin Cash SV—engaged in a hash war for control of the network. This conflict, also known as the hash war, was not just a technical disagreement but a battle of ideologies, economic incentives, and raw computational power. Understanding the events requires diving into the history of Bitcoin Cash, the philosophical split that led to the fork, and the dramatic showdown that ensued.
Background of Bitcoin Cash
Bitcoin Cash (BCH) emerged in August 2017 as a result of a hard fork from the original Bitcoin (BTC) blockchain. The primary disagreement was over scalability: the Bitcoin Core community advocated for SegWit and layer-2 solutions like the Lightning Network, while a faction led by miners and developers like Roger Ver and Jihan Wu insisted on increasing the block size limit to allow more transactions on-chain. The result was Bitcoin Cash, which initially adopted an 8 MB block size and later expanded to 32 MB.
However, Bitcoin Cash itself was not immune to internal conflicts. By 2018, two major factions had formed within the BCH community. One group, backing the Bitcoin ABC (Adjustable Block size Cap) implementation, sought to introduce various protocol upgrades, including a new opcode (OP_CHECKDATASIG) that would enable advanced smart contract functionality. The other group, championed by Craig Wright and Calvin Ayre, advocated for a loyalist approach that stuck closely to the original Bitcoin vision, calling their implementation Bitcoin SV (Satoshi Vision). The SV camp wanted larger blocks (up to 128 MB) and opposed what they saw as unnecessary changes to the protocol.
The Road to the Fork
Tensions escalated throughout 2018 as both sides failed to reach a consensus. The Bitcoin ABC team proposed a network upgrade scheduled for November 15, 2018, which included OP_CHECKDATASIG. Craig Wright and the SV faction strongly opposed this, arguing it would enable tokenization and bloat the blockchain. Wright also claimed that Bitcoin Cash should remain as close to Satoshi Nakamoto's original design as possible.
In an attempt to force their vision, the SV team announced they would initiate a hard fork on the same day, effectively splitting the chain into two competing cryptocurrencies. This was not merely a code fork; both sides aimed to become the sole legitimate heir of the Bitcoin Cash name. The hash war was born out of the need to assert dominance through proof-of-work—the side with more hash power would win the longest chain and claim the ticker symbol BCH.
The Hash War Begins
On November 15, 2018, both chains went live. The Bitcoin ABC chain, backed by mining pools such as BTC.com and ViaBTC, and supported by economic nodes like Bitmain and Roger Ver, initially had the majority of hash power. However, the SV camp, backed by Calvin Ayre's CoinGeek and Craig Wright's nChain, launched an aggressive campaign to overtake the ABC chain. They began secretly accumulating hash power from external sources, including renting hash power from SHA-256 mining pools like BTC.TOP and F2Pool.
The war escalated dramatically when the SV camp launched a series of attacks on the ABC chain, including intentionally reorganizing the blockchain (reorg attacks) to orphan blocks mined by the ABC side. This created significant confusion and risk for exchanges, miners, and users. For a period, the hash power on both sides fluctuated wildly, with SV at times surpassing ABC's hash rate.
Key milestones during the hash war included the point when the SV chain briefly overtook the ABC chain in cumulative difficulty and block height. However, the ABC chain had the advantage of the longest valid chain rule, as most miners and nodes initially considered ABC the legitimate continuation. The SV camp attempted to force a chain reorganization by mining empty blocks and using their hashing power to create a longer chain from their perspective.
Economic and Social Repercussions
The hash war had immediate economic consequences. The price of BCH dropped significantly as uncertainty deterred investors. Exchanges like Coinbase and Kraken suspended deposits and withdrawals until the chain stabilized. Miners faced a dilemma: which side to support? Their decisions were influenced by profitability, ideology, and the potential value of the tokens they would receive post-fork.
One critical factor was the role of exchanges in assigning ticker symbols. Major exchanges decided to temporarily label the two coins as BCHABC and BCHSV, with the ultimate winner to claim the original BCH ticker. This effectively created two separate assets. After the dust settled, Bitcoin ABC emerged as the dominant chain, with the majority of hash power and market capitalization. It retained the BCH ticker on most platforms.
Bitcoin SV, while still viable, became a distinct cryptocurrency with its own community and development roadmap. Craig Wright and Calvin Ayre continued to promote SV as the true Bitcoin, leading to further legal and ideological battles. However, the hash war demonstrated that raw hash power alone does not determine the legitimacy of a cryptocurrency—community support, exchange listings, and ecosystem adoption are equally important.
Technical Analysis of the Conflict
From a technical standpoint, the hash war was a fascinating case study in blockchain governance. The ability of a minority of miners to temporarily disrupt a network highlighted the fragility of proof-of-work systems when consensus fails. The SV camp employed a strategy known as "selfish mining" or "block withholding," where they would mine blocks privately and release them to create orphans. This technique, combined with massive hash rate rental, allowed them to momentarily gain an advantage.
Bitcoin ABC responded by implementing a checkpoint mechanism in their software to prevent deep reorganizations. This was a controversial move, as it introduced a degree of centralization by hardcoding a rule that rejected blocks from the SV chain. Nonetheless, it stabilized the ABC chain and prevented further attacks.
Another technical aspect was the use of the difficulty adjustment algorithm (DAA). Bitcoin Cash had recently implemented a new DAA to adjust difficulty more frequently than Bitcoin. During the hash war, the rapid shifts in hash power caused difficulty to fluctuate drastically, affecting block times and miner profitability. Both sides had to manage this volatility to maintain chain viability.
The hash war also raised questions about the security of rented hash power. Services like NiceHash allowed miners to rent hashing capacity on the spot market. The SV camp reportedly spent millions of dollars renting hash power, but this was a temporary measure. Once their funds depleted or the rental contracts ended, the ABC chain regained a stable majority.
Aftermath and Legacy
In the months following the hash war, Bitcoin Cash (BCH) continued to evolve under the ABC implementation, now led by developers like Amaury Séchet. The chain adopted further upgrades, including Schnorr signatures and token support via the Simple Ledger Protocol (SLP). Bitcoin SV, on the other hand, pursued aggressive scaling to 128 MB blocks and focused on enterprise applications, such as the Metanet and Tokenized protocols.
The hash war left a lasting impact on the cryptocurrency industry. It demonstrated the potential for contentious hard forks to result in violent hash power battles, encouraging developers and miners to seek more robust governance mechanisms. It also highlighted the importance of clear communication and timely coordination among stakeholders.
For investors and users, the event served as a cautionary tale about the risks of holding assets during a fork. Those who held BCH before the split received both BCHABC and BCHSV tokens, but the value of each was uncertain until the market resolved the conflict. Exchange handling of the split varied, leading to confusion and occasional losses.
Craig Wright's ongoing claims to be Satoshi Nakamoto were also intertwined with the hash war. While he failed to gain full control of Bitcoin Cash, his promotional efforts brought significant attention to Bitcoin SV. Legal battles between Wright and other crypto figures continued, further complicating the narrative.
Today, both BCH and BSV coexist as separate cryptocurrencies, each with its own community and development focus. BCH maintains a higher market cap and wider adoption, while BSV has a smaller but vocal following. The hash war remains a pivotal moment in crypto history, studied by academics and enthusiasts for its insights into decentralized governance and the limits of proof-of-work.
In retrospect, the hash war was not just about blocks and hashes—it was a struggle for the soul of a cryptocurrency. It underscored that technology alone cannot prevent human conflict; consensus requires alignment of incentives, communication, and sometimes, raw power. As the crypto space continues to mature, the lessons from the Bitcoin Cash hash war will remain relevant for any blockchain community facing existential decisions.
Source:Bitcoinist.com News