1. c5 ? Blocus  Ke4 ! [ and not 1...Ke2 ?  2. Bc4+ !  Ke1 

3. Bd2(Bxg3) # ]  2. Be6  Kd3 

3. Bxg3  Ke4  4. Nf2 #  model mate or 3...Ke2  4. Bc4 #

1. Bh5 ? Ke4 ! ( and not 1...c5 ? 2. Bd1 ! Ke4 3. Bc2 # ) 2. Bg4  Kd3(c5) 3. Bxg3 c5(Kd3) 4. Nf2 #

1. Bg6! Blocus.

Thematic variants :

1....c5     2. Nxg3 discovery + !  Kd4  3. Ne2 #  selfblock pawn c5.

1....Ke4  2. Ng7 discovery + !  Kd4  3. Ne6 #  pure mate.

Other variant :

1....Ke2  2. Nxg3+  Ke1  3. Bd2 #  pure mate.

Theme : The same white piece gives a discovery check, leaving a flight square for black King and

mates on this square.

Realized in Meredith.