Capablanca–Marshall, St. Petersburg 1914, a Petroff Defence Capablanca offers as an instructive study of the variation. His own public-domain notes from Chess Fundamentals (1921) appear below.
7.Bg5Played by Morphy, and a very fine move. The point is that should Black exchange Queens he will be a move behind in development and consequently will get a cramped game if White plays accurately.
7…Be6Marshall thought at the time that this was the best move and consequently played it in preference to Q x Q ch.
12.Bd3It is now time to examine the result of the opening. White's position is evidently free from danger and his pieces can easily manoeuvre. On Black's side we find his pieces bunched together too much, and the Queen in danger of being attacked without having any good square to go to. Besides, Black cannot Castle on either side with safety. Consequently we must conclude that the opening is all in White's favour.
12…g5To make room for his Queen, threatening also P - Kt 5.
13…O-OGiving up a Pawn in an attempt to free his game and take the initiative. It was difficult for him to find a move, as White threatened Kt - K 4.
16…c5In order to break up White's centre and bring his Knight to B 4 and thus lay the foundation for a violent attack against White's King. The plan, however, fails, as it always must in such cases, because Black's development is backward, and consequently his pieces are not properly placed.
18.Nd5A simple move, which destroys Black's plan utterly. Black will now have no concerted action of his pieces, and, as his Pawns are all weak, he will sooner or later lose them.
20…Qxd4The fact that he has to exchange Queens when he is a Pawn behind shows that Black's game is lost.
23…Bxd4The Knight was too threatening. But now the ending brought about is one in which the Bishop is stronger than the Knight, which makes Black's plight a desperate one. It is only because of its value as a study of this variation of the Petroff that I have given it.
José Raúl Capablanca, Chess Fundamentals (1921) · Public domain · source