Colle system. Attack on white fields.

5 Bd3 and 7 Bb5 cannot be right. Where does the bishop want to go?
9...a6? is reckless. 9...O-O is fine.

@tpr said ^

Where does the bishop want to go?

To d3 of course

"To d3 of course"

• Edgar Colle would agree, but 5 dxc5 a5 6 Bb5 seems better.
  Anyway if the bishop wants to go to d3, then it should not move again to go to b5, which it could do in 1 move.

Only when the opponent removed his bishop and closed the way back. Only then can you attack on the white fields, the defender has left.

@tpr said ^

5 Bd3 and 7 Bb5 cannot be right. Where does the bishop want to go?
9...a6? is reckless. 9...O-O is fine.

Bd3 allow to threat h7 in case of castling and can control the whole diagonale leading to h7. While in e2, the bishop can control only the diagonal leading to a6. For me, Bd2 is weaker than Bd3 in the Colle System because Bd3 can be used to build a Queen+Bishop battery in case of castling and you still keep another diagonal to move on in case of an opportunity.

Bd5 is simply a move developing in two time the bishop by using it to put the pressure on the Knight in c6. If black defended correctly, with a early a6 instead of Qc7, I would have played Ba4-Bc2 to keep the quality of the bishop, because in the Colle, the pawn structure is strong enough to keep it safe in case of a pawn wave.

"Bd3 allow to threat h7 in case of castling"

• Yes, that was the idea of Edgard Colle.

"While in e2"

• e2 is a passive spot.

"Bd5 is simply a move developing in two time the bishop"

• It is wrong to move the same piece twice in the opening. If the bishop belongs to b5, then 5 dxc5 6 Bb5 is right. If the bishop belongs to d3, then it should not move a second time. This is loss of tempo. If black had played 9...O-O instead of 9...a6? then black would be fine.

@tpr said ^

• It is wrong to move the same piece twice in the opening. If the bishop belongs to b5, then 5 dxc5 6 Bb5 is right. If the bishop belongs to d3, then it should not move a second time. This is loss of tempo.

That's the point of the Colle System and of some lines of the London. Because the opponent can't be sure about which option you're going to choose, which can lead often to inaccuracies or mistakes in pieces development while you're just fine with the bishop and the pawn structure. 9. 0-0 allow white to capture a pawn on c6 and it's not very fine for black on the queenside. Worse, the free spot in e5 is undefended after.

"the point of the Colle System"

• The main point of the original Colle system is to prepare e4, hence Bd3, Nbd2, Re1

"9. 0-0 allow white to capture a pawn on c6"

• Black is fine after that, he get the bishop's pair and Bc1 is undeveloped.