user23699: The standard London System consists of the setup moves: d4, Bf4, e3, Nf3, Nbd2, c3, Bd3. I'm wondering about the nuances of what the most accurate move order is to play it in. Here are some of my thoughts:

Some people like reaching the London via 1.d4 Nf6 2.Nf3, but I like playing 2.Bf4; that way, you can go for the more aggressive setup with 3.Nc3 against King's Indian players, potentially tricking them into a Pirc.

Against people who play symmetrically, ie. 1.d4 d5 2.Bf4 Bf5, I like playing an early c4 instead of c3 to break symmetry.

If White plays Nf3 early, Black can play a combination of Nc6-Nh5 to harass / potentially trap the London bishop (since the queen has lost vision of h5) and force it to move off its natural diagonal, which can be annoying.
[FEN ""]
1.d4 d5 2.Bf4 Nf6 3.e3 c5 4.Nf3 Nc6 5.Nbd2 Nh5

If Black follows the main line setup with d5/Nf6/c5/Nc6/Qb6, it seems more accurate to play Nbd2 before c3, in case Black decides to enter the sharp gambit lines with dxc5 / Qxb2.
[FEN ""]

d4 d5 2.Bf4 Nf6 3.e3 c5 4.Nf3 Nc6 5. Nbd2 Qb6 6.dxc5 Qxb2 7.Rb1


In the main line, most masters seem to prefer the move order with d4-Bf4-e3-c3-Nd2; I'm not sure why this is.
[FEN ""]

d4 d5 2. Bf4 Nf6 3. e3 c5 4. c3 Nc6 5. Nd2



Why do masters prefer the above move order, and what other nuances am I missing from my points here?

user23596: The early Nd2 gives some breathing room for your a1 rook
       [FEN ""]
       1. d4 d5 2. Bf4 Nf6 3. e3 c5 4. c3 Nc6 5. Nf3 Qb6 6. Qb3 c4 7. Qc2 Bf5 8. Qc1 (5. Nd2 Qb6 6. Qb3 c4 7. Qc2 g6 8. e4)

Notice how black cannot easily harass your queen and get a lead in development with Bf5 in the early Nd2 case

23699: <p>The standard London System consists of the setup moves: d4, Bf4, e3, Nf3, Nbd2, c3, Bd3. I'm wondering about the nuances of what the most accurate move order is to play it in. Here are some of my thoughts:</p>
<ul>
<li><p>Some people like reaching the London via 1.d4 Nf6 2.Nf3, but I like playing 2.Bf4; that way, you can go for the more aggressive setup with 3.Nc3 against King's Indian players, potentially tricking them into a Pirc.</p>
</li>
<li><p>Against people who play symmetrically, ie. 1.d4 d5 2.Bf4 Bf5, I like playing an early c4 instead of c3 to break symmetry.</p>
</li>
<li><p>If White plays Nf3 early, Black can play a combination of Nc6-Nh5 to harass / potentially trap the London bishop (since the queen has lost vision of h5) and force it to move off its natural diagonal, which can be annoying.</p>
<p>[FEN &quot;&quot;]
1.d4 d5 2.Bf4 Nf6 3.e3 c5 4.Nf3 Nc6 5.Nbd2 Nh5</p>
</li>
<li><p>If Black follows the main line setup with d5/Nf6/c5/Nc6/Qb6, it seems more accurate to play Nbd2 before c3, in case Black decides to enter the sharp gambit lines with dxc5 / Qxb2.</p>
<p>[FEN &quot;&quot;]</p>
<ol>
<li>d4 d5 2.Bf4 Nf6 3.e3 c5 4.Nf3 Nc6 5. Nbd2 Qb6 6.dxc5 Qxb2 7.Rb1</li>
</ol>
</li>
<li><p>In the main line, most masters seem to prefer the move order with d4-Bf4-e3-c3-Nd2; I'm not sure why this is.</p>
<p>[FEN &quot;&quot;]</p>
<ol>
<li>d4 d5 2. Bf4 Nf6 3. e3 c5 4. c3 Nc6 5. Nd2</li>
</ol>
</li>
</ul>
<p>Why do masters prefer the above move order, and what other nuances am I missing from my points here?</p>
 23596: <p>The early Nd2 gives some breathing room for your a1 rook</p>
<pre><code>       [FEN &quot;&quot;]
       1. d4 d5 2. Bf4 Nf6 3. e3 c5 4. c3 Nc6 5. Nf3 Qb6 6. Qb3 c4 7. Qc2 Bf5 8. Qc1 (5. Nd2 Qb6 6. Qb3 c4 7. Qc2 g6 8. e4)
</code></pre>
<p>Notice how black cannot easily harass your queen and get a lead in development with Bf5 in the early Nd2 case</p>
