Ruy Lopez: Morphy Defense, Modern Steinitz Defense

Key ideas for both sides

White

Castle with 5.O-O and play Re1, then c3 and d4, as the top engine line shows.
With 5.c3, White prepares d4 and keeps the a4 bishop. Watch for ...f5, a sharp try against this setup.
Do not play d4 and Nxd4 carelessly: Black's ...b5 and ...c5-c4 can trap a bishop on b3.
The 5.c4 line grips d5 and can answer ...Bg4 with h3 and a trade on f3.

Black

Develop with ...Nf6 and ...Be7, and use ...b5 only when the a4 bishop is ready to retreat to b3.
Against c3, consider ...Bd7 and ...Nge7, holding e5 with pieces before White pushes d4.
Remember the Noah's Ark idea: with the bishop on b3, ...c5 and ...c4 can shut it in.
Pin the f3 knight with ...Bg4 when White plays c4, and keep the light squares in mind.

Plans and pawn structure

The d6 pawn gives Black a solid but slightly passive center. White usually plays c3 and d4, keeping the bishop on a4 or b3, and then grows on the kingside with Nbd2-f1-g3. Black can choose between holding e5 with ...Bd7 and ...Nge7, or taking on d4 to open lines for the pieces. A quick ...f5 against c3 leads to sharper play where White's lead in development counts. If White trades on c6, Black keeps the bishop pair and recaptures toward the center.

What the engine plays from here

Stockfish 17.1 at depth 20 rates the position +0.39: a slight edge for White. Its three top choices for White:

+0.39 5.O-O Nf6 6.Re1 b5 7.Bb3 Be7
+0.33 5.c3 Nf6 6.O-O Nxe4 7.d4 Bd7
+0.21 5.c4 Bg4 6.h3 Bxf3 7.Qxf3 Nf6

Pawns, from White's side.

How it scores on lichess

1,582 rated lichess games reached this position; White scored 54.4%.

under 120056.0%

1200–159957.6%

1600–199952.9%

2000 and up52.1%

Light: White wins. Grey: draws. Dark: Black wins. About the sample.

Traps and pitfalls

Noah's Ark Trap (Black sets it)

White wins back the d4 pawn with 8.Qxd4, and Black traps the bishop on b3. The pawns on a6, b5 and c4 form a cage, and the bishop has no escape squares.

The Noah's Ark Trap explained

Where it goes next

Morphy Defense, Modern Steinitz Defense, Siesta Variation5.c3 · rare
Closed, Kecskemet Variation5.O-O · rare

How to play against it

As White, castle and play Re1 or c3 before d4. Avoid an early d4 and Nxd4 with the bishop going to b3, because ...b5 and ...c5-c4 can trap it. If Black plays ...f5 against c3, take on f5 and castle quickly.

Other lines with this name

The lichess opening list also files these lines under the same name, though they reach a different position: 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 d6 5.Nc3; 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 d6 5.c4; 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 d6 5.O-O.

Questions

What are the moves of the Ruy Lopez: Morphy Defense, Modern Steinitz Defense?

The Ruy Lopez: Morphy Defense, Modern Steinitz Defense starts 1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 d6. Its ECO code is C71, C72, C73, C74, C75.

Is the Ruy Lopez: Morphy Defense, Modern Steinitz Defense good for Black?

Stockfish 17.1 rates the position +0.39 at depth 20, which is a slight edge for White. In 1,582 lichess games from our sample, White scored 54.4%. Good for solid Black players who like a stable e5 pawn, but it gives White a free hand in the center and calls for patience.

What is the main idea of the Ruy Lopez: Morphy Defense, Modern Steinitz Defense?

Black adds ...d6 after the useful ...a6, so e5 is firmly held and the a4 bishop can be chased later with ...b5. White builds c3 and d4 and must avoid the Noah's Ark trap on b3.

What should White play next?

The engine's first choice is O-O, with c3 and c4 close behind. 5.O-O gets the king safe first, keeping c3 and d4 ready for later.

Updated October 2026. Sources and method.