What is the longest non-cyclic forced sequence of moves? I am looking for positions from where every move is forced up to a certain depth. If the original position (or one in between) occurs again, the sequence is finished there.
9 moves
In the linked thread (not quite a duplicate), a valid answer is posed to this question:

You mean like this?

[Title &quot;Vilhelm Röpke, Skakbladet 1942, Mate In 6&quot;]
[FEN &quot;K1k5/P1Pp4/1p1P4/8/p7/P2P4/8/8 w - - 0 1&quot;]


White mates in 6.


I guess that's 9 consecutive forced moves. It would be eleven except for black's choice of promotion piece on his fifth move. I don't know if it's a record, and I don't know who composed this classic chess problem.