The Van 't Kruijs Opening is an irregular chess opening defined by the move 1.e3. ECO code: A00.

History

The opening is named after Maarten van 't Kruijs (1813–1885), a Dutch chess master who was among the strongest players in the Netherlands in the mid-19th century. While 1.e3 is a sound move—it opens the diagonal for the dark-squared bishop—it is classified among the irregular openings because it does not immediately fight for central control with a pawn on the fourth rank.

Main Lines & Variations

After 1.e3, Black's most common responses are 1...d5, 1...e5, 1...Nf6, and 1...c5. The opening frequently transposes into standard systems:

• After 1.e3 d5 2.d4, the position resembles a Queen\'s Gambit structure where the c1-bishop is temporarily blocked behind the e3-pawn.

• After 1.e3 e5 2.d4, a reversed French Defence structure may arise.

• After 1.e3 Nf6 2.d4, various Indian Defence systems are possible.

Strategic Themes & Plans

White's primary advantage is extreme flexibility—the position can evolve into a Colle System, Stonewall, Queen\'s Gambit, or numerous other setups depending on Black's response. The drawback is that 1.e3 blocks the c1-bishop behind the e-pawn and surrenders the first-move initiative. Black achieves easy equality with any natural developing scheme. The opening is rarely seen at the professional level as an independent system, though it occasionally appears as a transpositional device.