The setup is similar to the London system with the difference that white hasn’t played Bf4. And if we compare it with the stonewall attack, then white hasn’t played f4 yet. But as we will see, in some lines this setup can also be converted into a stonewall attack.
Continuing from the above position, after 5…Nc6 6.Nbd2 Bd6 7.0-0 0-0 is the main line of the Colle system.
White plans to play central break e4 to free up his position. But first white must release pressure from the d4 pawn. The main line goes 8.dxc5 Bxc5 9.e4 and here, if black goes for endgame after 9…dxe4 10.Nxe4 Nxe4 11.Bxe4 Qxd1 12.Rxd1, this endgame is better for white.
After Bf4, white will have well-developed pieces while black has a major problem with the development of c8 bishop. That counts for really good chances for white.
So instead of 9…dxe4, the main line is 9…Qc7 10.Qe2 h6 and white has many options to continue here.
White can immediately start playing 11.b4 with idea of a4-Bb2 with plan for expanding on queenside. White can play 11.e5 which is a possible pawn sacrifice after 11…Ng4 12.Nb3 Bb6 13.Nbd4 Ngxe5 14.Nxe5 Nxe5 15.Bf4 f6 16.Rae1 with an objectively equal game.
After exchanges on e5, the material will be equal, but black will have two bishops advantage while white will have strong position in the center with d4 and e5 squares occupied.
In the previous line, black can also choose to capture with 6…cxd4. After 7.exd4 Bd6 8. 0-0 0-0 white has a slightly better game due to the semi-open e file and the unlocked bishop on c1.
Black will try to attack on the c3 pawn by playing a6-b5-b4 on the other hand white has a simple plan of Re1-Ne5 and if needed Nf1-g3 and Bf4 holding a strong control on e5 square.
Black can choose to postpone c5 and first develop his pieces. 1.d4 d5 2.Nf3 Nf6 3.e3 e6 4.Bd3 Be7 (or Bd6) 5.0-0 0-0 6.Nbd2 b6
and here white has a chance to convert into stonewall attack by playing 7.Ne5 Bb7 8.f4 Ne4 9.Nxe4 dxe4 10. Bc4
After 10…Bd5, black has nothing to fear. Game is equal.
Colle system against 1…Nf6
After 1.d4 Nf6 2.Nf3 e6 3.e3 b6 4.Bd3 Bb7 we have the Colle system against the queen’s Indian set-up. Similar to the London system, black keeps the flexibility of playing …c5 or …d5.
Possible line could go 5 0-0 c5 6.b3 d5 7.Nbd2 cxd4 8.exd4 Bd6 9.Bb2 with an equal game.
After 1.d4 Nf6 2.Nf3 g6 3.e3 Bg7 4.Bd3 d6 is the colle system against the king’s Indian defense. However black can play 4…d5, which is more suitable for black.
White’s plan is to play c4-Nc3-b3-Bb2. However, with the king’s Indian set-up black’s position is solid.
Game Played with Colle System
Here is classic game played between Gelfand, Boris (2703) vs Kramnik, Vladimir (2809)
Since this setup is very similar to the London system, white should also prepare that opening along with the colle system. By playing the Colle, white eliminates the possible weakness of b2 pawn which occurs in the London system.
On the other hand, the late development of white’s bishop on c1 gives black enough time to develop his pieces comfortably, and white doesn’t get as much control on the e5 square as he gets in the London system