Causeway

The Causeway is the only dry road through the Neck, a narrow, elevated log-and-plank road that runs through swamps and bogs, and its northern end is plugged by the ruins of Moat Cailin. Its strategic choke-point nature makes it the decisive gateway between the North and the southern kingdoms, and its capture by Roose Bolton's forces in A Dance with Dragons seals the return of Bolton power to the North and the final collapse of ironborn resistance in the region.

Geography and Strategic Importance

The Causeway is the sole dry route through the Neck, a vast, impassable morass of bogs, quicksands, and treacherous marshes. The road itself is a narrow log-and-plank construction, and its northern terminus is blocked by the three ruined towers of Moat Cailin: the Gatehouse Tower, the Drunkard's Tower, and the Children's Tower. Any army approaching from the south must pass beneath and between these towers, exposing its flanks to attack from the other two. The swampy ground on either side of the Causeway is an endless morass of suckholes, quicksands, and glistening green swards that turn to water underfoot, infested with venomous serpents, poisonous flowers, and monstrous lizard lions. The swamp-dwellers, the bog devils, are also a constant threat, using poisoned arrows. The Causeway's narrowness and the ruins' positioning make it a formidable defensive position that has never been taken from the south.

The Siege and Fall of Moat Cailin

By the time of A Dance with Dragons, Moat Cailin is held by a dwindling garrison of ironborn under the command of Ralf Kenning, left behind by Victarion Greyjoy when the Iron Fleet sailed for the kingsmoot. The garrison is starving, sick, and demoralized, with men dying from poisoned arrows and the foul water. Ralf Kenning himself is dying from a poisoned wound, his body swollen and crawling with worms. The ironborn are trapped, with Roose Bolton's army to the south and Ramsay Bolton's forces to the north. Theon Greyjoy, now calling himself Reek, is sent by Ramsay to negotiate their surrender. He pretends to be a prince of the Iron Islands and convinces the remaining ironborn that they have been abandoned. After killing the dying Kenning, Theon secures the surrender of the garrison, promising them safe passage. The ironborn are then led out of the ruins, only to be slaughtered by Ramsay's men, their corpses nailed to stakes along the road as a grisly warning.

Aftermath and Significance

The fall of Moat Cailin opens the way for Roose Bolton's army to march north from the Twins and join forces with his son Ramsay. This allows Bolton to consolidate his power in the North, as he can now bring his full strength to bear against his enemies. The Causeway, once the North's greatest defensive asset, becomes a highway for Bolton's forces, and the flayed man of House Bolton is hoisted above the Gatehouse Tower in place of the golden kraken of Pyke. The event marks the end of ironborn power in the North and sets the stage for the Bolton's confrontation with Stannis Baratheon.