haha, nice
Longest checkmate problem-290 move

Indeed, the theme of losing a tempo via a long king journal is probably the easiest and best way to lengthen a problem (not to discredit Blathy - quite the other way around, he exploits a good idea to the max).
In this study black prolongs the inevitable death with the help of the 3 h-pawns by no less than 260 moves! (of course the 50 move rule could apply but then again this is a study and the position is illegal to begin with).

The possition is illegal because one of white bishops must be promoted pawn, yet there are 8 white pawns on the board. 50 move rule doesn't aply here: it is draw if no piece is taken OR PAWN MOVED. Here black pawn moves every 17 moves.
On second thought, if the possition is already illigal, why can we put black pawns on h4, h3 and h2? That would make problem 392 moves long, if I calculated correctly!

@Caliphigia, 3 years later, white has 8 pawns but only has two bishops. This wouldn't be the reason for an illegal position, being that black does have 3 bishops, but only 7 pawns. PS, good calculations.

Last time this problem popped up I looked for the version with a legal position (supposedly it's easy to fix) but I couldn't find it.

@Caliphigia, 3 years later, white has 8 pawns but only has two bishops. This wouldn't be the reason for an illegal position, being that black does have 3 bishops, but only 7 pawns. PS, good calculations.
Dude, two white bishops are on the same colored squares.

@Caliphigia, 3 years later, white has 8 pawns but only has two bishops. This wouldn't be the reason for an illegal position, being that black does have 3 bishops, but only 7 pawns. PS, good calculations.
Dude, two white bishops are on the same colored squares.
Dude, one of them is promoted. :P
Otto Blathy was born in Tata, Hungary on August 11, 1860 and he is credited for creating a mate in 290 moves. This problem is the longest checkmate problem and Blathy won a prize for this work in 1929. The position is not legal (easy retro analysis) and it is easy to convert it to a legal position, but the original Blathy position is shown. The analysis/solution given here was done by Cyril Banderier in 1992 and has been online since 1998. Mr. Blathy died on September 26, 1939 in Budapest.