Arimaa/Attacking/Techniques

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If an attacking piece is taken hostage by the enemy elephant, and the attacking elephant defends the hostage, that is an elephant deadlock. An elephant-less attack may then occur on the other wing. If the hostage is a camel, and the hostage-holder's own camel is already on the other wing, the hostage-holder's position may be strong. If the hostage is a horse, however, and both camels are free, the attacker likely has the advantage. This informs opening strategy. A horse typically advances ahead of its camel, and a defender usually tries to block an attacking horse rather than hostage it with his elephant. A camel may then advance behind its horse; EMH (elephant-camel-horse) attacks are common in the opening. Once strong pieces are captured or marginalized, further attacks may require less strength.

Course of an EMH attack[edit]

With camels on opposite wings, each side will likely advance on its camel wing, with a potential EMH attack in mind.

Prelude: horse to a6[edit]

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If a silver horse occupies b6, a gold horse may initially advance to a6, hoping to later get onto b6. Likewise, a silver horse may go to h3 in hopes of later getting onto g3. Anticipating such a countermove, Gold blockaded h3 with rabbits; the silver horse can still reach h3, but that will now take at least six steps. Gold is willing to let his eastern rabbits be pulled while he develops in the west.

Occupy key square[edit]

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In this diagram, Gold has just played the pull-and-replace Mb4ns hb6s Ha6e, getting his horse onto b6. Note that the a5 rabbit allowed the camel to return from b5 even with the silver elephant on c5. It is common for at least one weak piece to advance on the a-file, and for weak pieces to occupy c3 and two adjacent squares, to give the gold camel greater mobility with the silver elephant nearby.

The gold camel now threatens to pull the silver horse south and take it hostage, giving Gold strong threats in both western traps. Silver to move can prevent this by retreating the silver horse to a6, from where it might later get back onto b6 via a pull-and-replace.

If not needed as a direct trap defender, the silver elephant might occupy b5 to block the gold camel. In that case, Gold could still continue the attack, but might do better to move his camel east and create a second threat.

See #Maneuvers for more examples of ways to get a key square.

Rotate out elephant[edit]

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Once one safely occupies two key squares of an away trap, an ideal continuation is to replace the friendly elephant with a weaker piece. From this position, Silver played 11s De3e ed3e dd4s cf6e, defending c3 with a camel and dog while also preventing a one-turn capture in f6, which the silver elephant can now defend. The gold elephant must stay by c3 to prevent material loss, so this rotation gives Silver a strong elephant mobility advantage. In other cases, the departure of the attacking elephant might also free the defending elephant, but the lasting shared control should still give the attacker an advantage.

Which piece should replace the attacking elephant depends on what defenders are nearby. In this case, no gold horse was near d3, so a silver dog could do the job. The presence of the gold dog on d2 might have allowed Gold to reclaim d3 with a pull-and-replace (12g Ec4ew dd3n Dd2n), but here that fails to 12s ee3n Dd3e dd4s dd5s, after which the silver dog on d4 blocks the pull-and-replace.

Alternative: switch wings with the camel[edit]

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After getting a horse onto g6 in this game, Gold could not easily rotate out his elephant. With g7, f6, and f7 blockaded, the gold horse could not soon reach f7, which might have been a better attacking square under the circumstances. With the elephants deadlocked in the northeast, it was up to the camels to do something elsewhere. After helping the gold horse reach g6, the gold camel hurried west to counter the silver camel.

Some noteworthy features of the position:

  • The g5 rabbit stops Silver from regaining g6 with a pull-and-replace. This defensive pull-and-replace is a common idea, as is blocking it by occupying g5.
  • Silver must keep a piece on d6 to stop Gold from flipping the f6 horse. If Gold could remove the silver horse from the northeast, the silver army would be unbalanced, and a gold dog could become a strong eastern attacker. Such a flip occurred on 12g in this game, giving Gold strong trap control.
  • If Gold has time to advance the h2 rabbit to h6, Silver will be cramped in the east.

Defences[edit]

Counterattack[edit]

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Silver defended f6 and attacked f3.

Often, the best response to a trap attack is a trap attack. A counterattack usually occurs on the other wing, but can occur on the same wing if that is where the opponent is weakest. In this game, Gold attacked f6 and then Silver attacked f3; Silver's attack is far stronger, and the silver elephant could likely stop any further attack by Gold. With his home forces unbalanced, Gold could do little about Silver's eastern advances. Had the gold camel been in the east, it would have been much harder for Silver to counterattack there, and Gold might have quickly cleaned up if the silver elephant went west.

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Gold answers an EMH attack with an MH attack, while the gold elephant defends. (Game)


If an EMH attack occurs on each wing, the one who attacked first will likely be ahead. An MH attack may be a better response to an EMH attack, as the elephants would be deadlocked on the EMH attack wing, and the MH attacker's camel would be the strongest piece on the other wing.

Bring the camel[edit]

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The silver camel aims to get the gold horse off of b6. (game)

When a horse attacks, the defender's camel might move through the back ranks to take it hostage. The attacking elephant might try to block this, perhaps by stepping directly into the camel's path or by pulling a back-rank rabbit.

Even if the camel can reach the attacking horse, the attacking elephant may be a problem for the camel; a horse-by-camel hostage is often hard to maintain. Furthermore, the attacking side might retreat the horse a square or two while preparing an attack on the other wing, to overload the defending camel.

In this game, the gold camel punished Silver advances on both wings.

Blockade squares[edit]

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Gold and Silver have each used phalanxes to block access to key squares. (Game)

The defender might blockade squares around the trap to deny the attacker room to maneuver. The trap square itself is also crucial; an attacker might move through a trap to get where it wants to go. A defending piece on a trap can at least slow this down, and might later move off to defend against capture.

Rabbit blockade[edit]

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Gold's own rabbits block his planned eastern attack.

In this game, Gold advanced a rabbit to h5 so that his camel could move through g5, perhaps for a pull-and-replace. Silver foiled this plan by pulling another gold rabbit to g5. Since rabbits can't retreat, the g5 and h5 rabbits now block other gold pieces. Silver should keep these gold rabbits in place, so as not to reopen an attack path for the gold camel or allow the h6 horse to retreat.

A flank rabbit advance may aid an attack, but the attacker should take care not to let a second rabbit get pulled up if the two rabbits together might block the attack.

Hostage[edit]

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Gold's horse hostage slows Silver's attack in the east, and Gold has a threat in the west.

An attacking piece might be taken hostage. An attacker should not take for granted that a horse-by-elephant hostage would be weak. By the time the silver horse was hostaged in this opening, the gold camel had advanced and couldn't be captured in exchange for the silver horse alone; having pieces on c6 and f5 complicated things for Silver.

Maneuvers[edit]

Here are some ways a trap attack might begin. There is no simple recipe for attacking: any maneuver might be thwarted, and the whole board must be considered before pieces are committed to a local fight. The following are simply some common tactics that both sides should be aware of.

The positions are all from linked games, but are transferred to the northwest quadrant, with colors swapped when necessary.

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The horse dives through the trap: Hb5en cc7n Hc6n. This may be dangerous for Gold if the silver camel is at home; even if the camel can't immediately take the gold horse hostage, the silver elephant may block the horse from retreating while the silver camel comes west. To prevent such a dive, the defender can use a phalanx to blockade c7, or blockade the trap itself.
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Gold to move defeats the c7 phalanx with Ed6e cd7s cc7e Hc6n. The gold piece on c5 is essential; without it, the horse would be lost when the elephant stepped away. Were Silver to move here, the gold horse could be framed, although Gold might soon break that frame via a pull-and-replace.
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Silver has blockaded b7 against the advanced gold horse, but Gold defeats the blockade with Ed7s dc7e rb7e Ha7e.
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Gold to move does a pull-and-replace (Mb4ns hb6s Ha6e), creating potential threats in both c6 and c3, as the silver horse could be pulled further south. Silver could then do a pull-and-replace to frame the gold horse; the frame would not hold for long, but might buy Silver time. If Silver is to move, she might place her elephant on b5 to block the gold camel, and perhaps counterattack in the east.
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Gold to move could retreat his camel and move the a6 horse to b6, or he could move the camel through the trap. Silver to move, however, could blockade the gold camel and horse with rc8w rd7s Rc5w ec4n or rc8w rd7s ec4wn.
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Gold just played Rb2nn db6e Mb5n. The a7 horse prevents a camel hostage, at least on a6. In the game, Gold subsequently pushed the silver horse down the a-file and took a strong horse hostage.
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Silver has blocked the gold camel, but Gold to move can still play a pull-and-replace with Ed6we hb6e Ha6e. Silver to move can prevent this by occupying the trap, but a silver piece on c6 might risk being flipped toward c3.
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Gold plays Ec5we hb6s Ha6e. This might seem easy, but since the gold elephant is not on d6, the silver camel might come over and threaten to hostage the gold horse. The gold elephant probably wants to move to d6 regardless, so this maneuver loses time even if the silver camel doesn't cause a problem.

If this pull-and-replace is not Gold's first priority, he might step his elephant to b5 with a threat to pull the silver horse on the next turn. If the silver elephant could then reach c5, however, that would ruin Gold's plan and marginalize the gold elephant.

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The gold camel has just moved to c6, threatening to reach c7 or help the a6 horse onto b6. The advanced gold horse makes a western camel hostage unlikely. The camel is however vulnerable to a fork between c6 and f6; Silver can now play hb6n eb5n Mc6e eb6e, though the camel could then escape. If the silver elephant were more centralized, it might pull the camel out for a fork. An attacker in the trap must beware of a fork.

If the silver elephant leaves, the silver horse might be pushed toward c3.

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From this position the gold elephant occupied b6, pushing the defending horse away; the c4 gold horse then took b6 in what amounted to a multi-turn push-and-replace. A free silver camel could have punished the gold elephant's decentralization, but in this case the camels were deadlocked on the other wing.