An Upside Down Christmas Tree

T.R,Dawson Flakirk Hearld 1914

Mate in 2 white to move

(solution below)

We are going to work this out from retrograde analysis.Where could have blacks last move been???He can't have moved his king,as that would result as a impossible dould check if gone to d8 or f8 and for d7 and f7,the e-pawn is blocked and could not have moved.And also not the b7 or h7 pawns as they have never moved!The only moves are d7-d5 and f7-f5.Both would be mate in 2,but there is only one solution.Both moves can mate,with cxd6 then d7 or gxf6 then f7 mate.

The white pawns must have taken 10 captures to reach their positions,and that is every piece that are gone,so the c8 bishop could not have been taken on its starting square,therefore the last move must have been f7-f5!

Solution

1.gxf6   any pawn move

2.f7#