In this article we will see different fortress positions for minor pieces (usually Defender Side) against Queen in pawn less endgame.
Queen vs. Two Bishops
Bishop must be arrange in a way so that stronger side king can not attack them. You can set up the fortress in 4 corners.
Giambattista Lolli has given following position in his book Osservazioni teorico-pratiche sopra il giuoco degli scacchi (English: Theoretical-practical views on the game of chess), published 1763 in Bologna. Which has been used in almost every chess endgame book to describe fortress against queen for two bishops.
Two Bishop Fortress
1.Qd7+ Kg8 2.Qe6+ Kg7 3.Qd6 Bf7 4.Kf5
and again with 4.... Bg6+ 5.Kf4 and Black again gets Lolli Position. and there is no another way to win this game for white. You can your self analyse the position or can take help of computer in case you have any doubts. 5...Kf7 6.Qd7+ Kf8 =:=
In the next part we will see fortress for two knights.