Many players lose their focus over exchanging Queens. Some run to trade, believing this may help them get safely to an endgame, even if they ruin their position in the process. Others are afraid to trade, because the Queen is the only attacking piece they feel confident about.
When Seigbert Tarrasch introduced the Tarrasch Defense to the Queen's Gambit, many skoffed because Black often accepts an isolated QP, a weakness in the endgame. Tarrasch answered, "Between the opening and the ending, the gods have placed the middlegame." Of course, an isolated QP is often an advantage in the middlegame.
One should exchange Queens, or avoid the exchange, based on the given position. Is it good for you, or bad? Don't think the Ladies' disappearance means the middlegame is over, or even that sacrifices are out of the question. The following is a correspondence game against a strong "A" player:
1.d4
Nf6
2.Bg5
The Trompowsky Attack was a favorite of mine for several years
2...Ne4
3.Bh4
d5
An older line of defense; more common are [3...g5
or ; 3...c5
]
4.f3
Nd6
5.Nc3
c5
6.e4!
TN - a new move I introduced here. The usual move was [6.dxc5
Nf5
7.Bf2
d4
8.Ne4
and Black will have some counterplay.]
6...dxe4
Now the game is similar to the Blackmar-Diemer Gambit, in this case good for White because Black's pieces are not well placed for that opening. [The alternative was 6...cxd4
7.Nxd5
Qa5+
8.Kf2
e5
(If Black tries 8...Qc5
9.b4!
Qc6
10.Bb5!
and White wins the Q with a Knight fork.) 9.b4!
Nxe4+
10.fxe4
Bxb4
11.Qh5
Bd6
12.Bc4
0-0
13.Nf3
and White has material AND the attack, winning easily.]
7.dxc5
Nf5
8.Qxd8+
Black was probably counting on the exchange to relieve his game, which is more cramped than in the old 6 dxc5 line. White exchanges with gain of tempo, though, as Nimzowitsch taught, and retains attacking chances.
8...Kxd8
9.0-0-0+
Nd7?!
[9...Bd7
was somewhat better because c8 is freed for the King, making him a bit safer.]
10.Bg5!
exf3
[10...e3
, slowing down White's development, was more prudent]
11.Nxf3
f6
Black has problems already. Neither B can move, between his two Ns there is only one safe move - to the rim at h6, and his Rs can only take a meaningless side-step.
12.Nd5!!
A stunning piece sacrifice after trading Qs. [12.g4
was my original idea when I played 10 Bg5: 12...Nh6
(or 12...fxg5
13.gxf5
and White is already winning, for example 13...g4
14.Ne5
with a massacre.) 13.Bxh6
gxh6
14.Nd4
e5
15.Ne6+
Ke7
16.Bc4
with a beautiful position for White, but Nd5 is even better.]
12...Rb8
Moving out of one potential N fork and daring White to leave his B en prise for another move. [If 12...fxg5
13.Nxg5
with threats of Nf7 or Nge6 and Ndc7]
13.Bb5!
Taking the challenge and continuing to develop aggressively while Black is hog-tied.
13...fxg5
At this point, he may as well accept the sacrifice.
14.Nxg5
e6
Black has to get his pieces out somehow
15.Nxe6+
Ke8
16.Rde1
Kf7
The only move, but it merely postpones the end. [16...Be7
17.Nxg7+
Nxg7
18.Rxe7+
and wins; 16...Ne7
17.Ng5
h6
18.Nc7+
Kd8
19.Nge6#
would have been a pretty finish.]
17.Nd8+
Kg6
[Or 17...Kg8
18.Bc4+-
with a deadly double check to follow.]
18.Nf4+
Kg5
[Not 18...Kh6??
19.Nf7#
; Mate also follows on 18...Kf6
19.Re6+
Kg5
20.Nf7+
Kxf4
(20...Kh4
21.Ng6+!
hxg6
22.Re4+
Kh5
23.Be2#
; 20...Kg4
21.Be2+
Kh4
(21...Kxf4
22.Rf1#
) 22.Ng6+
hxg6
23.Re4#
) 21.Rf1+
Kg4
22.Be2+
Kh4
23.Rf4#
Notice that in all these lines, Black's pieces are all merely spectators as his King flees for his life.]
19.Nf7+
Kg4
[If Black tries 19...Kxf4
20.Rhf1+
Kg4
21.Be2+
Kh4
22.Rf4#
; or 19...Kf6
20.Nxh8+-
wins a Rook while the attack continues.]
20.Rhf1
Black resigns, as his King is surrounded by the entire White army - you can work out the mates for yourself.
The whole attack began with the exchange of Qs. 1-0