Solution:
1.Ra4
(a) Rc4 (b) 2.Ba5 (c) Bd6/e5
3.Bd8+ (d) Be7/f6 4.Sd4! Rc1+ 5.Kh2 Rh1+
6.Kxh1 h2 7.Kxh2 ~ 8.Sxf5#
(a) Threatens 2.Be7#. 1.Sd4? (thr. 2.Sxf5#, if 1…h2 then 2.Sxf5+ Kh3
3.Sg5#) but 1…Rc5! or 1…Bd3! Notice that
if 1…Rc1+ 2.Rxc1 Bd3 and mate in six more moves.
(b) 1…Bc4? 2.Sd4
Rc5 3.Bxc5 h2 4.Sxf5+ Kh3 5.Sg5#. But moving away the wR from a1 has created a
new obstacle.
(c) Theatens 3.Bd8+
Se7 4.Bxe7# 3...Sf6 4.Bxf6#. 2.Sd4?
(thr. 2.Sxf5#) now 2…Bd3 is not playable, and if 2…Rc5? then 3.Sxf5+ Rxf5 4.Be7# but 2…Rc1+ 3.Be1 Rxe1#. Notice that mating White is Black’s unique defense (Berlin
(d) 3.Sd4? the initial defensive moves have been elliminated but
this move unpins the bR and the Berlin
