B45 Sicilian Defence

ECO code B45 covers the Four Knights Variation of the Sicilian Defence. It arises after 1.e4 c5 2.Nf3 e6 3.d4 cxd4 4.Nxd4 Nc6 5.Nc3 Nf6, or by the 4...Nf6 5.Nc3 Nc6 move order. Black develops both knights before moving the d-pawn and aims for ...Bb4 and ...d5 to strike at e4. White has two sharp tries. 6.Ndb5 eyes the d6-square, and 6...Bb4 answers by pinning the c3-knight and adding pressure on e4. 6.Nxc6 bxc6 7.e5 Nd5 gains space and drives the f6-knight away. The recapture towards the centre leaves Black a compact pawn mass that supports a later ...d6 or ...d5.