The blocksize war
The 2015–2017 fight over who rules Bitcoin. Users won.
In plain words
Blocks were filling. One camp — most big companies and many miners — wanted bigger blocks: cheaper payments, accepting that verification would get heavier and fewer people would run nodes. The other camp said Bitcoin's point is that no one decrees its rules, and anyone can check them. Corporate takeover attempts — XT, Classic, Unlimited, SegWit2x — all failed against ordinary users running full nodes. SegWit activated instead; the big-block movement forked off as Bitcoin Cash and faded.
Why it matters
- It settled Bitcoin's constitution: nodes enforce the rules; miners and companies don't.
- The clearest demonstration that Bitcoin cannot be bought or voted over by hashrate.
- Its scars shaped everything after — SegWit, Lightning, upgrade caution.
Numbers that matter
- 2015–2017 — the war's span.
- August 1, 2017 — Bitcoin Cash split off.
- November 2017 — SegWit2x canceled; the war effectively over.
Go deeper
Updated 2026-07-30