Introduction

The London system is a 1.d4 opening for white, it is an opening system. An opening system is usually an opening for white. In a system opening, in most cases, the moves that the player plays are not related to what the opponent plays. Because of that, the opening is friendly for new chess players because it doesn't require the person to memorize that much theory.

The opening creates a solid structure for white, developing most of its powerful pieces, and creates a link between multiple pieces to reduce the amount of weakspots in the system significantly. The pawns in the middle solidifies center control, while having the opportunity for Nfe5, creating an outpost for the knight. But the opening itself is more in a steady pace, there are no immediate pressure in the beginning, giving black a lot of freedom for development. The Queen side for white pieces is not as developed, as the queen side bishop and knight are developed towards the center of the board. While there are some aggressive lines in London that could catch black off guard, like establishing an attack with Qf3 and Qh3, the opening overall lacks offensive diversity.

Main Line ● Indian Setup(...g6) Jobava London

Pros:

-Can be played in a variety of situations -Solid structure -Spatial pressure, reduces black pieces's play options

Cons:

-Less attacking opportunity -Lack of pressure in early stages of the game -Weak queen side attack

London System: Main Line

White opens with d4, taking center space and building the foundation for future developments. White will create structure by supporting this pawn. In the mainline, black plays d5, which is a common response. White then plays Bf4 to accelerate London system. In London system, we want to build a "pawn pyramid" by playing e3 and c3, but we need to develop our bishop before that so we don't lock them in and limit their development. In the original mainline, white plays Nf3, but the new engines has proven that Bf4 is more accurate.

1.d4 d5 2.Bf4

In the mainline, black responds with Nf6. White immediately support our bishop by playing e3, at the same time closing the pawn structure. Black responds with c5, we play c3 to support pawn on d4. One thing to notice is that if black doesn't play c5 as a response, white don't have to play c3 immediately. Instead, white could play Nf3 first, developing king side. But if black plays c5, white have to immediately respond with c3.

2.Bf4 Nf6 3.e3 c5 4.c3

Black plays Nc6, a common move to develop their knight and support the center. With the choice to play Nh5 in the future the attack the bishop on f4. White plays Nd2 to develop our knight and support e4 square. Black plays e6 to create a pawn chain structure, which is solid for defense. e6 also allows the bishop on f8 to develop. White then develops their other knight with Ngf3, with the potential jump to e5, creating an outpost.

4.c3 Nc6 5.Nd2 e6 6.Ngf3

Black plays Bd6 to activate their bishop. This move attacks our bishop, white can utilize this opportunity and slide the bishop back to g3. This point of this move is that if they take the bishop, white can take back with our pawn on the h file, which then creates an open file for our rook. Giving them more attacking opportunities on the king side, like Bd3 and Qh5 in the future. Black then castles king side, to protect their king and prepare to connect and activate their rooks. The special notation "O-O" indicates short castling. Long castling's notation is "O-O-O".

6.Ngf3 Bd6 7.Bg3 O-O

After black chooses to castle, white plays Bd3. The point of this move is to activate the bishop, putting it in a comfortable position where it can directly attack the h7 square, preparing for a push on the king side with h4. Black plays b6 to make space for the bishop to develop, we play Qe2 to protect the bishop on d3, also providing the possibility of an e4 push in the future. Black then plays Bb7, to put pressure on the diagonal, defending the e4 push. This is called a fianchetto, where you move your b or g pawn up a square, and put the bishop behind the pawn (Bb7, Bg7, Bb2, Bg2).

8.Bd3 b6 9.Qe2 Bb7