London System
D02 · 1. d4 d5 2. Nf3 Nf6 3. Bf4
The same setup against almost anything, which is the appeal and the limit.
Analysing from a photo?
This page needs a FEN or a board you set up by hand. The app reads a position straight from a photograph of a real board or a screenshot, and keeps your saved positions between sessions.
The idea
White develops the dark-squared bishop to f4 before playing e3, avoiding the problem that troubles most d4 players: the bishop getting locked behind its own pawn chain. The setup with d4, Nf3, Bf4, e3, c3 and Bd3 can be played against nearly any Black reply, which is why it has become the most popular practical choice below master level.
Typical plans
- Build the standard setup, castle short, then expand in the centre with e4 at the right moment.
- Attack on the kingside with Ne5, Qf3 and a pawn to h4 once Black has castled short.
- Trade the dark-squared bishop for a knight when Black offers, and take the doubled pawns.
What goes wrong
- Playing the setup on autopilot. It is a system, not a substitute for looking at the position.
- Allowing an early Bf5 or Bg4 by Black, which neutralises much of White's plan.
- Assuming the London is drawish. It has real attacking chances and real ways to be worse.
Using the board above
The board starts at the position after 1. d4 d5 2. Nf3 Nf6 3. Bf4. Play the continuation you normally meet, then ask the engine what it would do. That is more useful than reading a line, because it answers the question you actually have, which is what happens in the position you keep reaching.
One caution worth carrying into it: an engine evaluates an opening on the assumption that both sides then play perfectly. A line rated a tenth of a pawn better whose middlegames you have never played is worth less to you than a line rated slightly worse that produces positions you understand. More on that here.