Chess Board
[ECO code C23]
BISHOP'S OPG. TRANSPOSITION
PHILIDOR VAR. (towards) PETROFF GAMBIT
White correctly developed his king's knight to support 5.P-Q4, and enabled castling.
Black now transposes lines, pushing his Queen's Pawn out one rank to Q3(d6), doubling his KP support and freeing his QB for development.
    White  Black    Transp.White Black
 1. P-K4   P-K4		  (1.)
 2. B-B4   B-B4		  (2.)
 3. P-QB3  Q-K2?!   (3.	Kt-KB3 P-Q3)
 4. Kt-KB3 P-Q3	    (4.	P-QB3  Q-K2)
Continue: Transpose or Undo or Jump or Clear