In chess, a fortress is an endgame drawing technique in which the side behind in material sets up a zone of protection around their King that cannot be penetrated by the opponent. The player can then draw merely by passive defense.

Here is a typical example where White is ahead by a Queen for two pieces and would normally win, but Black has set up an impenetrable fortress and can just move his King around in the corner to draw.

Black draws because he is in a “fortress”.

Test your understanding of this concept by looking at the following diagram.

Should White play:

A 1.Nh1,
B 1.Ng4,
C 1.Nxe4 or
D 1.Nd1

If 1.Nh1 Be5 wins.
If 1.Ng4 Bg7 2.Kd2 Kc4 3.Kc2 Kb4 4.Kd2 Kb3 5.Kd1 Kc3 6.Ke2 Kc2 7.Ke1 Kd3 wins.
If 1.Nd1 Kc4 wins.
If 1.Nxe4! Kxe4 2.Kf1 Kxe3 3.Kb1 and White just hides in his fortress on h1 and draws.

Here is a composed problem where White is way down on material but can draw by building a fortress. Can you find the drawing plan?

White to Play & Draw

Answer:
1.Ba4+!! Kxa4 2.b3+ Kb5 3.c4+ Kc6 4.c6+ Kd7 5.e6+ Kxd8 6.f5 drawn.