Add a piece, then #2

Now I would like to revise my previous statement:
There are 16 pawns ergo no pawn was promoted. There are two knights so 11 of 12 missing pieces were captured /we have to determine what is the one that was not captured/. That is 5 Black and 6 White (see below).
The pawn at h3 came through d7 with four captures of pieces (excluding the dark-squared bishop this leaves us with a knight, queen or rook left). The pawn at h6 came with four captures from d2 (so eight captures total until this moment, four White and four Black). Pawn at g4 came from h2 with one capture (a piece was captured at g3). Total of 9 captures so far (2 more left). Pieces left /excluding the two knights in the final position/ for White the dark squared bishop and another piece, for black the light squared bishop; the pawns at "a", "b"- files changed places through two captures from the Black side, so the piece that is left is the Black light squared Bishop. The only places from which it cannot prevent 1.Ne8 and 2.Nc7# by delivering check are "e8" and "a2", however the bishop cannot be placed at "e8" so it should be placed at the "a2" square.
And so, unless I have miscalculated something, the mystery should be revealed.

Originally posted by ilywrin
Now I would like to revise my previous statement:
There are 16 pawns ergo no pawn was promoted. There are two knights so 11 of 12 missing pieces were captured /we have to determine what is the one that was not captured/. That is 5 Black and 6 White (see below).
The pawn at h3 came through d7 with four captures of pieces (excluding the dark-squared bishop t ...[text shortened]... e "a2" square.
And so, unless I have miscalculated something, the mystery should be revealed.

What happends if you place the Bishop on h5?

Originally posted by BigDoggProblem
What happends if you place the Bishop on h5?

Well, to be honest I have missed that option 🙁
Assuming we have placed the bishop at "h5" and it is White to move, let's try to determine what was Black's last (legal) move? The Bishop and the knight and the pawn at c5 are sealed so the only viable option is either b5-b4 or a5xb4;
Since axb4 is easily discarded (the White pawn must have reached the "a7" spot thus the "a"-file was unobstructed) it remains only b5-b4. But then there were two captures of light-squared White pieces (a6xb5, and b7xa6) while as I have concluded in my previous post there were a light-squared piece and the dark-squared bishop left from the White's side. So the position with the black Bishop at "h5" is illegal 😉
Does that sound right?

Originally posted by ilywrin
Well, to be honest I have missed that option 🙁
Assuming we have placed the bishop at "h5" and it is White to move, let's try to determine what was Black's last (legal) move? The Bishop and the knight and the pawn at c5 are sealed so the only viable option is either b5-b4 or a5xb4;
Since axb4 is easily discarded (the White pawn must have reached the " ...[text shortened]... e's side. So the position with the black Bishop at "h5" is illegal 😉
Does that sound right?

Yes, that's right.

Good work.

This problem was composed by T.R. Dawson in 1922.