Thematic tries:

1. Nd4 ?  threat : 2. Kd7 and 3. Ne6 #

1....Be5 ! (1....Bg1 ?  2. Nf3 ! and mate in 2)  2.Nf3  Bf4 z  3. Kd7  Be3 !! z and no mate in 2. 

1. Ne1 ?  threat : 2. Nd3  Bd6 z  3. Kd7 (3. Kxd6 ?  stalemate) and mate in 2 with 5. Ne6 #

1....Be5 !  2. Nd3  Bd4 z  3. Kd7  Be3 !! z and no mate in 2.

 

1. Nb4 !  threat : 2. Na6 !  Bd6 z  3. Kd7 and mate in 2 with 5. Ne6 #

A) 1....Bb8 !

     2. Nd3 !!

     2. Na6 ?  Ba7 ! z  3. Kd7  Bb6 !! z  4. ?

     2....Bd6 z (firstly decoved to b8, B cannot go to d4 and therefore loses the focus.  See thematic   try 1. Ne1 ?).

     3. Kd7 !

     3....B~

     4. Nc5 or Nf4  and  5. Ne6 #

B) 1....Bg1 !

     2. Nc6 !!

     2. Nd3 ?  Bd4 ! z  3. Kd7  Be3 !! z  4. ?

     2....Bh2

     3. Kd7 !

     3. Nd4 ?  Be5 !  4. ?

     3....Bc7(e5,g1) (decoved to h2, B cannot go to b6 and therefore loses the focus.)

     4. Nd4(d8)  and  5. Ne6 #

Focal play in miniature form with a decov of Bishop in order to prevent a new focal opposition after

a change of the initial mating square (A line)  (Author)