Helsinki theme
A black piece sacrifices itself to a white pawn to enable it to vacate a square for a black pawn which, in turn, vacates a square for the black king.
Zajic, Helmut
Schach-Report, 1995
1st HM
h#3 b) wBa5→g1
(6+13)
a) 1.Qc6
dxc6
2.d5
d4+
3.Kd6
Rxh6#
b) 1.Rg4
fxg4
2.f3
Rg8
3.Kf4
Bh2#