Previous posts discussed the lines 10...Bd6 and 10...Be7 in the Seidel Hall line of the Teichmann Exchange, occuring after 1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 4.f3 exf3 5.Nxf3 Bg4 6.h3 Bxf3 7.Qxf3 c6 8.g4 e6 9.g5 Nd5 10.Bd3
We learned that black faces an uphill struggle to obtain equality.
This current blog focuses on another variation, occuring after black's 10...Bb4.
The lines with black playing Bb4 are often condemned in the Blackmar Diemer theory, but are actually very hard to play against, as black might exchange a piece and comes closer to a potentially winning endgame.
11.Bd2 has some merit as it allows the standard attach Qe4 followed by h4 and h5 if black were so kind as to play 11...00, eg 11...00 12.Qe4 g6 13.h4 (diagram) 13...e5 (trying to open the e-file) 14.h5 and white is better, eg 14...exd4 15.hxg6 Re8 16.gxf7+ and white mates in 10.
The problem is that black can simply play a waiting move 11...Nd7 (instead of the committal 11...00) and white must declare his intentions first - with black getting the better play.
11.a3 is also insufficient, eg 11...Bxc3+ 12.bxc3 Nxc3 and there is no way to create an immediate threat to exploit the two pawn deficit, eg 13.00 00 14.Bxh7+ Kxh7 15.Qxc3 Nd7 and black is better
So 11.00 ( with the automatic reply 11...00 ) is actually forced for white, after which 12.Ne4 is the only move that does not permit the exchange of pieces. Black's bishop on b4 now seems ridiculous.