| 1.Rg6? A (2.Re6#, Bd6#) f4#! x 1.Rb1? B (2.Rb6 ~ 3.Re6#) 1...b5 2.a:b6 e.p. ~ 3.b7 ~ 4. b8Q, B# 1...b5! y 1.a5! (2.Rb1 B (3.Rb6 ~ 4.Re6#) 2...b5 y 3.a:b6 e.p ~ 4.b7 ~ 5.b8Q, B#) 1...Bd1 2.f4+! 2...e:f4 e.p 3.Rg6! A (4.Re6#, Bd6#) 3...f4+ x 4.Kf2+ Be2, Kf5 5.R[6]g5# 2...g:f4 e.p 3.R:f5+! [3.Rg1? g6!] K:f5 4.Rg1 ~ 5.R[1]g5# 1...g3 2.f:g3! (3.Rg6 (4.Re6#, Bd6#) 3...f4+ 4.g:f4+ Kf5 5.Rg5#) 2...b5 3.a:b6 e.p ~ 4.b7 ~ 5.b8Q, B# Berlin theme with avoidance of mate to the wK by vacation of f2, so the unpinned bPf5’s move is turned into a check to the wK. Pape theme (double en passant capture of a pawn) in the sub-variations after 1...Bd1: - opening of a white battery line on the e-file after 2...e:f4 e.p, followed by 4.Kf2+; - opening of a white line on the g-file after 2...g:f4 e.p, followed by 4.Rg1. Mates on the same square (g5) with: - switchback of wRg5; - arrival of wRe1 on a square vacated by wRg5. A full-length threat with a third e.p. capture. | 
