411 REFERENCE · Wikibooks
Chess Opening Theory/1. b3/1...e5/2. Bb2/2...Nc6/3. d4
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Modern variation A01 Nimzowitsch-Larsen → Modern variation → 2...Nc6
3. d4?
A mistake. Rather than spending their time continuing development of their pieces, White initiates trades in the centre. After 3...exd4 4. Bxd4 Nxd4 5. Qxd4, White has given up central control and the bishop they had spent time developing to the powerful long diagonal. 5...Nf6 6. e4?! d5 7. e5 Ne4! with the threat of ...Bc5!.
References
See also
Nimzovich-Larsen Attack