Marshall Variation

The Marshall Variation is the most direct treatment of the Modern Variation. After 3. d4 Black simply recaptures with 3...Nxd5, restoring material balance without the queen sortie. The knight on d5 is a target, though, and White's usual plan is to gain time and space with c4 and Nf3, which can leave Black short of room. The most common reply is 4. c4, closely followed by 4. Nf3, and engines give White a slight edge.

After 4. c4 the knight must choose a square. 4...Nb6 is considered the most active retreat. 4...Nf6, sometimes called the Marshall Retreat Variation, was rated by Tartakower as the soundest option. 4...Nb4, the Kiel Variation, is a speculative attempt that rarely appears in practice, since 5. a3 N4c6 6. d5 leaves White well ahead in the center. With 4. Nf3 Bg4 5. c4 Nb6 White can try the sharp 6. c5, after which 6...N6d7 is the accurate retreat.