---
id: "1997-05-11-deep-blue-kasparov"
url: "https://postcutoff.com/e/1997-05-11-deep-blue-kasparov/"
as_of: "2026-11-13T13:49:00+01:00"
date: "1997-05-11"
date_precision: day
category: milestone
importance: 5
confidence: high
status: [Confirmed]
sources: 2
editor: human editor
human_review: null
version: "2026-10-04"
---

As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/e/1997-05-11-deep-blue-kasparov/

# IBM Deep Blue defeats world chess champion Garry Kasparov

IBM's Deep Blue won a six-game rematch against reigning world champion Garry Kasparov 3.5–2.5, the first defeat of a world champion by a computer under standard tournament time controls.

## Key facts
- Final game played 11 May 1997 in New York
- Score: 3.5–2.5 to Deep Blue
- Used massively parallel brute-force search with custom chess chips
- Kasparov had won the first match in 1996 (4–2)

## What happened

In a rematch in New York, Deep Blue beat Kasparov, winning the decisive sixth game.

## Why it matters

A landmark public moment for AI, though achieved by specialized search rather than learning — a contrast with AlphaGo/AlphaZero two decades later.

## Your AI and this story

- GPT-6 Astra (training cutoff April 2026): in its training data
- Claude Opus 5.5 (training cutoff June 2026): in its training data
- Gemini 4 Hydrogen (training cutoff March 2026): in its training data
- Grok 4.7 (training cutoff May 2026): in its training data

## Sources

1. [IBM: Deep Blue](https://www.ibm.com/history/deep-blue) (ibm.com, official)
2. [Wikipedia: Deep Blue versus Garry Kasparov](https://en.wikipedia.org/wiki/Deep_Blue_versus_Garry_Kasparov) (en.wikipedia.org, discussion)

## Changes

- 2026-09-29 (filed): Created

## Related

- 2016-03-15: [AlphaGo defeats Lee Sedol 4–1 at Go](https://postcutoff.com/e/2016-03-15-alphago-lee-sedol/index.md)