Julia's Fairies

Do You know the Marine pieces? – Part II

PAP-photo-MarineDo You know the Marine pieces?
(Part II – Poseidon, Marine Knight, Marine Pawn)

IGM Petko Petkov




The second part of my article about Marine pieces relates to three pieces that are little known in practice: Poseidon (PO) – the Marine King, the Marine Knight (MS) and the Marine Pawn (MP in Popeye, Pion marine=PM in WinChloe). These pieces are presented here in accordance with two programs: version 3,23 of the WinChloe program (the first program where they have been implemented) and version 4,63 of Popeye!

Further, this article demonstrates these figures mainly in schemes and educational examples, without any combinations with other fairy pieces or conditions. Therefore, the main goal of this article is not to show masterpieces in this field, but to demonstrate mainly simple, elementary rules and effects of every marine piece in its “solo role”. Why solo? In order to absorb more easily the rules for movement of each of these pieces. De facto, in contemporary fairy-composition Marine pieces almost always work in “cooperation” with some other fairy pieces, conditions, etc.

By the by, an official theory (concept) of Marine pieces and even of their names (!) currently doesn’t exist. For this reason, there are many differences in definitions and names, which we can meet at various sources. There are a lot of very difficult debatable theoretical and practical questions related to usage of Marine pieces and other fairy conditions. This matter has been studied a little and almost forgotten.

Working with WinChloe you should know that this program uses the concepts of Christian Poisson concerning PO, MS and MP pieces. Working with Popeye 4,63 you should accept the principles of this program. There are some differences between WinChloe and Popeye regarding castling, play with Marine Pawns etc.  





The Marine King is named “Poseidon” (or “Neptune”, but this name is rarely used).
The Poseidon moves like a King when not capturing, and captures adjacent pieces like a Locust. In WinChloe Christian Poisson has defined Poseidon as a King/(0,1) + (1,1) Equilocuhopper Shooter. In both programs – WinChloe and Popeye – the symbol of Poseidon is  PO.

According to the definition, in the scheme N21 the white Poseidon (g2) can play either as a normal King: 1.POf3; 1.POh3 or as a Locust after 1.POxg3-g4.

The move 1.POxf2-e2?? is illegal because of self-check.
The move 1.POxh2?? is impossible, because it does not have the Locust’s character!

The black Poseidon (c6) can play as a normal King: 1.POb5; 1.POd5; 1.POd7 or as a “Short Locust”: 1. POxb6-a6; 1.POxb7-a8, POxd6–e6.


The white and black Poseidon can be located on adjacent squares as shown in scheme N22. Here the white POh1 is not in check, of course, because the capture POg2xh1 is impossible. The black POg2 is also not in check, because the move POh1xg2 is not possible (the square f3 is occupied). The POg2 cannot play 1.POh2?? or 1.POg1?? because of the illegal self-checks from the POh1 (POxh2-h3 and POxg1-f1 respectively). But here we see the existence of a strange white battery, created by Rf3 (forward piece) and POh1 (rear piece). Every move of the Rf3 will lead to check from the  POh1! Batteries having a Poseidon as the rear piece are very interesting mechanisms! But mate in 1 is possible only after 1.Rf4#! After this move the square g4 is guarded and Black cannot answer with 1…POxg3-g4.


Castling with a Poseidon is not possible according to Popeye 4,63 but it is possible according to WinChloe if the other orthodox rules are fulfilled! Therefore in Scheme N23 1.0-0# is possible only according to WinChloe. Popeye gives here “no solution”!

Сastling with POe1 and a white Triton on h1 is impossible according to both programs! 


If we use a Poseidon as a main thematic piece, a very interesting theme is Blocks of Poseidon that deprive it of the possibility of capturing enemy pieces as a Locust. Some light examples follow:

In N24  in the beginning White can’t give mate: 1. Qg1+? POxg1-f1!; 1.Qg2+? POxg2-f3!; 1.Qh2+? POxh2-h3! Therefore one of the squares f1, f3 or h3 must be blocked: I. 1.d1=S! 2.Se3 3.Sf1 Qg1#! because the capture POxg1-f1 is not possible; analogously: II. 1.d1=R 2.Rd3 3.Rf3 Qg2#; III. 1.d1=B 2.Bg4 3.Bh3 Qh2#


The thematic tries in N25 are: 1. Qe2+? POxe2-d3!; 1.Qe1+? POxe1-d1; 1.Kg2+? – an illegal move, because of 1…POxg2-h3!; 1.Kg1+? – also not possible because of 1…POxg1-h1. After 1.Qe3! – zugzwang – the black S blocks four (!)  squares: 1…Sd3 2.Qe2#, 1…Sd1 2.Qe1#, 1…Sh3 2.Kg2#, 1…Sh1 2.Kg1#. The last two variations show an interesting and important idea: The orthodox King mates Poseidon after blocking him! 


In N26 after 1.POh1! Black is stalemated, because the Bh3 is pinned by the POh1!  This pin by a Poseidon is also a nice and paradoxical motive!



marine-horseV. MARINE KNIGHT


The Marine Knight moves as Knight provided the destination square is vacant, but captures an enemy on (1,2) by leaping to (2,4) – which again must be vacant. (Note: in some sources this piece is named Squid (SQ), in the WinChloe program – Cavalier marin (CM). In Popeye this piece is also named Marine Knight with a symbol MS).

In N27 the MSf1 plays without captures as an orthodox S: 1.MSd2 or 1.MSh2. But it can capture as a “S-Locust” by 1.MSxe3-d5! because the square d5 is free. Pay attention to the direction of this piece: f1-e3-d5 which is a straight line! (As by a Nightrider!). Not possible is 1.MSxg3?? because the square h5 is occupied.


N28 is an old and good educational problem. Thematic tries: 1.MSg3? but 1…MSc5! and 1.MSf2+? but 1…MSd6! – the black defences are blocks of the “Locust’s squares” c5/d6. After 1.Se5! [2.g6#] the black MSs play to c7 with the idea of playing 2…MSxe6-g5!, with a block of g5 that closes the battery line. But here White uses the removals of the MSs: 1…MSec7 2.MSf2#, 1…MSac7 2.MSg3#. This small Meredith is a very good demonstration of the most important motives in the play of Marine Knights: batteries and blocks of the MS’s directions!

In the already well known N29  we see Annihilation captures on c4/f5 which by their character are special openings of battery lines! Another very interesting Annihilation occurs when the MSf2 captures the Pe3 with the idea of vacating a square for the white mating MSs. The fine black second moves prevent self-checks to the white King:  a) 1.MSg4 MSa5 2.MSxe3-c2 MSxc4-e3 #; b) 1.MSc2 MSg7 2.MSxe3-g4 MSxf5-e3 #  PAP-Marine-N29

The double battery MS/MS is an interesting and unexplored possibility, as are almost all double batteries using Marine pieces. 

A typical and lightweight example is N30I. 1.Bg4 f7 2.Bf3 MSxd3-b4#; II. 1.Sb4 Bc1 2.Sd5 MSxf5-h4# – interchange of functions between both MS. Another specific idea here is the vacation of squares f6 and d2.


If you use a neutral MS, an interesting position with neutral double battery and at the same time with reciprocal pins of these pieces is possible! N311.g1=nMS Kh2+ 2. nMSh3 Kg2=! Stalemate because both  MS are reciprocally self-pinned! Of course, this idea can also be realized with other neutral or half-neutral marine pieces.


sea-world-pawnVI. MARINE PAWN


The Marine pawn (MP in Popeye, PM in WinChloe) moves as a pawn, but captures by hopping over its enemy diagonally forward – in the manner of a draughtsman (or checker) but without the draughtsman’s repeated captures. MP may be captured en passant by an enemy Pawn or Marine Pawn and may capture en passant an enemy Pawn or Marine Pawn.
The Marine Pawn can promote to Siren, Triton, Nereid, Marine Knight or to any other  fairy or orthodox piece that stands on the board. (Note: in some old English sources the Marine Pawn is named “Prawn” with symbol PR).


In N32 MPf2 can mate after: 1.MPxg3-h4#! Other moves with wMPf2 are also possible, but they are useless: 1.MPf3+? Kg1! (or 1…Kh1!); 1.MPf4+? Kg1!
MPd7 can capture by 1…MPxc6-b5 and 1…MPxe6-f5. Kg1!

Attention!! Here the white Ka1 is not under check, because the capture 1…b2xa1?? is impossible!


Important notice!

According to WinChloe, a MP cannot capture en passant and cannot be captured en passant! According to Popeye en passant is always possible when one or two Marine Pawns participate in the capture!

So in scheme N33:
There is no solution according to WinChloe because after 1.Bf1+ MPb5 the capture 2.cxb6 (e.p) is not allowed! We have the same situation if a white Marine pawn is on c5.
But Popeye gives: 1.Bh3-f1+! MPb7-b5 2.cxb6 ep#. With white MPc5 we have also: 1.Bh3-f1+! MPb7-b5 2.MPxb6-a7 ep#!



When can an orthodox pawn promote to a marine piece? Here the standard rule for promotion to a fairy piece applies: the pawn can promote only to the kind of Marine pieces that are present on the board!

For example: if on the board there are two marine pieces – Siren and Triton (the color does not matter here!) and a white Pawn on f7, then six promotions are possible – 4 orthodox into Q, R, B, S and two fairy – into Siren and Triton! 

In N34 the solution is: 1.a8TR!! Ka1 2.Rc1#. Pay attention  that here it is not possible to play 1.a8SI?? Ka1 2.Rc1# because the white Pawn is not allowed to promote to Siren, because such a piece is not present on the board! 


When can a Marine Pawn be promoted and to what pieces?
The Marine Pawn can be promoted into four main marine pieces: Siren, Triton, Nereid, Marine Knight plus any other pieces (orthodox or fairies) that are located on the board!

In N35 every move of MPg7 gives mate. But how many solutions are there? The answer – only 4 – after promotions to the main Marine pieces: 1. g8=SI#, 1.g8=TR#, 1.g8=NE# and 1.g8=MS #! No other promotions, orthodox or fairy, are possible here!!


Another situation is demonstrated in diagram N36. How many solutions are there? At first we realize the four marine promotions with MPc6: 1.MPxd7-e8=SI#; 1.MPxd7-e8=TR#; 1.MPxd7-e8=NE#; 1.MPxd7-e8=MS#. According to marine rules, we have the right to promote MPc6 into all other pieces (orthodox or fairy) present on the board. Here we have 3 such pieces (except Kings): Queen, Bishop, Nightrider. Therefore, three additional promotions are possible: 1.MPxd7-e8=Q#; 1.MPxd7-e8=B#; 1. MPd7-e8=N#.



The next easy problem nicely demonstrates the basic rules that we have talked about. N371.MPb3 MPxb3-c4 2.MPb1=TR MPxb5-a6 3.TRb7 MPxb7- c8=SI#.
Some explanations are needed here: Firstly, Black does not have the right to promote to Rook (with the idea of 3.Rb7) because there is no such orthodox piece on the board! Also impossible is 3…MPxb7-c8=Q#?? because White doesn’t have the right to promote to Queen!


The 3rd part of this article will be dedicated to some “non-classical” Marine pieces: Marine MAO and Marine MOA (implemented in both programs – WinChloe and Popeye).

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May 8, 2013 08:37

N.24 is very good with three nice under-promotions. It is interesting that the B/R promotions and continuations are naturally forced without use of the white king !

May 8, 2013 08:39

I would have assumed that a Marine Pawn will promote to Marine pieces only. It is surprising that promotion any piece (fairy or orthodox) is possible. Perhaps it is one of those undefined areas.

May 8, 2013 14:20
Reply to  Julia

I was comparing with Chameleon pawn 🙂

Nicolas Dupont
Nicolas Dupont
May 8, 2013 14:04

Very nice educational article! In N25 the white King is in fact a Poseidon too…

Arno Tüngler
Arno Tüngler
May 8, 2013 14:10
Reply to  Nicolas Dupont

No, it is an “orthodox” king but was falsely given the PO mark in the solution…

Arno Tüngler
Arno Tüngler
May 8, 2013 17:32
Reply to  Julia

The same is true for the illegal moves of the wK…

May 8, 2013 14:30

hm….. Just curious. Are there Marine pieces which move like Queen/Rook/Bishop but capture the hurdle by jumping to any square beyond? Seems the logical variant on the analogy of Grasshopper/Lion.

May 8, 2013 15:15

Here is a try for an educational Marine PG!

PG 9.0
Marine Pawns

1.d4 g5 2.d5 Bg7 3.d6 Bf6 4.dxe7-f8=MS Qe7 5.Qd4 Qe5 6.Kd2 Ke7 7.Kd3 Ke6 8.Bd2 Se7 9.Be1 Rxf8

Schnoebelen Marine Knight (a promoted unit is called “Schnoebelen” when it is captured without having moved).

Indeed, after Qe7, f8 can’t be a Rook a Queen a Marine Rook or a Marine Queen. After Ke7, f8 can’t be a Bishop or a Marine Bishop. After Ke6, f8 can’t be a Knight so must be a Marine Knight! (d4 is occupied).

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