1.
[
{F:B}{B:K2k4/1pN5/3p1p1p/3P1P1P/7P/8/4P3/8 BLACK}
{V:Despite their length, serieshelpmates are usually quite easy to solve. The technique is the same as for helpmates, first the mating position must be identified and then the method of reaching it determined. Serieshelpmates lend themselves to unusual effects involving pawn promotion. This is one example. Serieshelpmate in 30.;b7b5;Correct;Incorrect.;It is a fairly obvious guess that White will mate by Ne6 after the squares c8, d7, e7 and e8 have been blocked. This means that all the black pawns will promote during the solution. The only problem is to work out which pawn promotes to which piece.}]

2.
[
White will mate by Ne6 after Black's four pawns have promoted and occupied the squares c8, d7, e7 and e8. At present only one Black pawn can move, so the first four moves are easy.]

3.
[
{S:b7b5}
1...b5]

4.
[
{S:b5b4}
2...b4]

5.
[
{S:b4b3}
3...b3]

6.
[
{S:b3b2}
4...b2]

7.
[
{F:B}{B:K2k4/2N5/3p1p1p/3P1P1P/7P/8/1p2P3/8}
Now Black faces the first promotion decision. After the pawn promotes, it will have to free another pawn as it moves towards its final destination. The obvious pawn to take is the one on f5, but should Black promote to a bishop or a queen? If Black takes a queen, and then plays ...Qxf5, then he cannot move to c8 (as this would be check) and it is no good blocking d7, because then Ne6 won't be mate. This suggests that a bishop is the correct choice.]

8.
[
{S:b2b1}{D:100}{X:b1}{P:BBb1}
5...b1B]

9.
[
{F:B}{B:K2k4/2N5/3p1p1p/3P1P1P/7P/8/4P3/1b6}
{S:b1f5}
6...Bxf5
The bishop should not move to d7, as this would prevent the final mate.]

10.
[
{S:f5c8}
7...Bc8]

11.
[
{S:f6f5}
8...f5]

12.
[
{S:f5f4}
9...f4]

13.
[
{S:f4f3}
10...f3
Now Black has to choose whether to promote on e1 or on f1. The answer comes from considering which type of piece will capture White's pawn on d5 to release the d6-pawn. It cannot be a bishop or queen, because this would give check, so it must be a rook or a knight. A rook appears possible, since afterwards it could move to e5 and e8, but this appears unlikely because after ...Rxd5 and ...Re5, there is no visible reason why Black should not play either ...d5 or ...Re8 next (the order of Black moves is always unique in a serieshelpmate). This suggests that a knight takes on d5, which is plausible because it could move to its final destination (e7) in only one move.]

14.
[
{S:f3f2}
11...f2]

15.
[
{F:B}{B:K1bk4/2N5/3p3p/3P3P/7P/8/4Pp2/8}
{S:f2f1}{D:100}{X:f1}{P:BNf1}
12...f1N]

16.
[
{S:f1e3}
13...Ne3]

17.
[
{S:e3d5}
14...Nxd5]

18.
[
{S:d5e7}
15...Ne7]

19.
[
{S:d6d5}
16...d5]

20.
[
{S:d5d4}
17...d4]

21.
[
{S:d4d3}
18...d3
Again, Black has a choice of promotion square, but now it is easier. By promoting to a queen on e1, Black can remove the pawns on h4 and h5 without loss of time, and then head for e8.]

22.
[
{S:d3e2}
19...dxe2]

23.
[
{F:B}{B:K1bk4/2N1n3/7p/7P/7P/8/4p3/8}
{S:e2e1}{D:100}{X:e1}{P:BQe1}
20...e1Q]

24.
[
{S:e1h4}
21...Qxh4]

25.
[
{S:h4h5}
22...Qxh5]

26.
[
{S:h5e8}
23...Qe8
Now the last pawn heads for the first rank.]

27.
[
{S:h6h5}
24...h5]

28.
[
{S:h5h4}
25...h4]

29.
[
{S:h4h3}
26...h3]

30.
[
{S:h3h2}
27...h2]

31.
[
{F:B}{B:K1bkq3/2N1n3/32/7p/8}
{S:h2h1}{D:100}{X:h1}{P:BRh1}
28...h1R]

32.
[
{S:h1d1}
29...Rd1
Finally...]

33.
[
{S:d1d7}
30...Rd7]

34.
[
{S:c7e6}
31 Ne6 mate.
The curious feature of this problem is that each of the four black pawns had to promote to a different piece.]
