Wiki / Events / Block size war

Block size war

From the Bitcoin Takeover Wiki · ✓ 6 sources · 2 podcast anchors · built 2026-11-13

The 2015–2017 fight over Bitcoin's 1 MB limit that produced the first durable chain split.

◆ Takeover vieweditorial · opinion, labelled

Fork Wars is the long-form version of this article, with a dated timeline, a stance board for every major actor and the two books side by side. The wiki entry is the short version that the terminal can quote.[2][4]

Contents

  1. Summary
  2. Big-block proposals
  3. Resolution
  4. Heard on Bitcoin Takeover
  5. References

Summary

For roughly two years, from 2015 to the summer of 2017, Bitcoin users argued over the 1 MB block size limit. One side wanted it raised so that on-chain payments stayed cheap; the other wanted it kept and capacity added through Segregated Witness and second layers such as Lightning[1]. The full dated history, with podcast quotes and listen links, is on Fork Wars[2].

Big-block proposals

Bitcoin XT (BIP101, Gavin Andresen and Mike Hearn) proposed 8 MB blocks doubling every two years until 2036; Bitcoin Classic settled on 2 MB; Bitcoin Unlimited dropped fixed numbers for "emergent consensus". None reached activation[1].

Resolution

In June 2017 Bitcoin ABC, led by Amaury Séchet, published a user-activated hard fork specification as a counter to BIP148[1]. Bitcoin Cash split on 1 August 2017; SegWit locked in on Bitcoin on 9 August and activated at block 481,824 on 24 August 2017[3]. Jonathan Bier, author of The Blocksize War, discussed the period on Bitcoin Takeover S16 E60[4].

Heard on Bitcoin Takeover

On S17 E35 (August 2026), Vinny Lingham argued: “We have the crypto ecosystem because the block sizes on Bitcoin was constrained.”[5]

References

  1. btkBitcoin Cash: The Big Block Breakaway (BTCTKVR: Forks!) [archived]
  2. btkFork Wars: the block size war timeline (Bitcoin Takeover) [archived]
  3. btkBitcoin: All the Hard Forks and Soft Forks (BTCTKVR: Forks!) [archived]
  4. episodeS16 E60: Jonathan Bier on Bitcoin Civil Wars & BitMEX Research▶ listen at 2:13:25timestamp transcript-derived, pending a listen [archived]
  5. episodeS17 E35: Vinny Lingham on what the block size limit produced▶ listen at 9:05timestamp transcript-derived, pending a listen [archived]
  6. primaryBitcoin commit a30b56e, 15 Jul 2010 (adds MAX_BLOCK_SIZE = 1000000) [archived]

Related

Bitcoin
The original chain. Every UTXO fork in this wiki shares its history up to a split block.
Bitcoin Cash
The big-block fork of 1 August 2017, Bitcoin's first durable chain split.
Bitcoin SV
The nChain-backed split from Bitcoin Cash in the November 2018 “hash war”.
Roger Ver
Early Bitcoin investor and leading Bitcoin Cash advocate; co-author of Hijacking Bitcoin (2024).
Categories: Events
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