TITLE: Is 39 moves the longest a chess game can go moving only pawns?
QUESTION [17 upvotes]: I've thought of a few different ways a chess game could go on moving only pawns, but I've only counted moves in one scenario:

Both White and Black take 16 moves to line their pawns at the middle of the board.
With a series of orderly captures in 8 moves, White and Black each wind up with 4 pawns each.
Taking care to threaten the rooks first, White and Black move their pawns within striking distance of the opponent's non-pawn pieces. This would take 16 moves (bringing the total up to 40), except that...
As soon as a White pawn threatens the Black king, Black would be forced to move the queen, a bishop or a knight to protect the king.

Have I thought through this scenario correctly? And even if I have, might could there be a scenario in which moving something other than a pawn could be put off longer?

REPLY [7 votes]: You can do better by having pawns move more before being captured.
1-4   b2-b6     g7-g3
5     hg        ab
6-9   g3-g7     b6-b2
10    g7xh8N    b2xa1N
11-15 g2-g7     b7-b2
16    g7xf8N    b2xc1N
17-21 a2-a7     h7-h2
22    a7xb8N    h2xg1N
23-26 e2-e6     c7-c3
27    dc        fe
28-31 c3-c7     e6-e2
32    c7xd8N    e2xd1N
33-37 c2-c7     e7-e2
38    f2        e2xf1N
39-42 f3-f7+    d7-d3