|Although this article is based on canonical information, the actual name of this subject is pure conjecture.
The assault on the Targaryen fleet was a naval engagement fought during Daenerys Targaryen's war for Westeros where the Iron Fleet, commanded by Euron Greyjoy, the King of the Iron Islands, attacked a portion of the Targaryen fleet under the command of his niece, Yara Greyjoy, herself an ally of Daenerys Targaryen.
After murdering Balon, Euron becomes the new King of the Iron Islands. Realizing their uncle to be a dangerous man, Yara and Theon flee, stealing 100 ships of the Iron Fleet with their loyalists, and sail to Meereen, where they make a pact with Daenerys.
Euron forms an alliance with the Lannisters. He proposes to Cersei, but she declines. In order to solidify the alliance, Euron decides to bring Cersei "a priceless gift".
Daenerys, meanwhile, lands at Dragonstone with her allies. In the chamber of the Painted Table, they discuss their war plans. Daenerys orders Yara, Theon, Ellaria, and the Sand Snakes to go to Dorne with their ships to gather and consolidate their forces, at the suggestion of Tyrion Lannister.
During the vaoyage, the Black Wind is suddenly rammed. Yara and Theon run up onto the deck to see the Silence, the flagship of their uncle, attacking them, along with the rest of the Iron Fleet attacking theirs. Euron locks the Silence onto Black Wind with his corvus and boards, along with the rest of his soldiers and they begin to fight Yara and Theon's loyal ironborn warriors. Tyene Sand runs onto deck, but Yara sends her back down below to protect Ellaria. Her sisters and fellow Sand Snakes, Obara Sand and Nymeria Sand, however, remain on the deck, fighting against Euron's men. All the while, trebuchets from Euron's fleet launch fireballs into Yara's ships, setting them afire and sinking them.
Euron cuts down several of Yara and Theon's men with his axe, but it is buried too deep into the skull of one of the men he kills and he is unable to pry it out. As he struggles to get it out, he is suddenly grabbed by Nymeria's whip around his throat; unfortunately, the attack only enrages Euron and he charges at Nymeria, hitting her in the face, distracting her long enough to get the whip from around his throat. However, he was then attacked by Obara, who cuts his back with her spear. However, he is able to dodge her other attacks and knocks her to the ground with her own spear, snapping it in half with her back before impaling her with the two halves of her spear and lifting her in the air. Nymeria sees this and runs towards Euron, stabbing him with her knife. Euron snatches her whip, however, and chokes her to death with it. Meanwhile, Tyene and Ellaria are captured by Euron's men. Ellaria tells them to kill them and be done with it, but the tongueless crew of the Silence only smile and bring them on deck to Euron.
Meanwhile, Yara watches on as her fleet is burnt and destroyed by Euron's. She continues cutting down Euron's men with her sword; when she catches sight of Euron, she leaps onto him, knocking him to the ground. However, Euron pushes her off and retrieves his axe, and the two engage in a brutal melee while Euron's men finish off his niece's. Euron beats her and holds his axe at her throat, tauntingly challenging Theon to come and save her. Theon, watching his men being slaughtered and tortured by Euron's, drops his sword and jumps overboard. Euron laughs madly and takes Yara to the Silence. He has the corpse of Nymeria hung from the front of Black Wind with Obara above it, the two halves of her spear keeping her up. Theon watches on in Blackwater Bay as the Silence sails away to King's Landing.
Yara's fleet has been destroyed almost completely. Only "two or three" ships escaped; one of those rescued Theon.
Euron returns to King's Landing triumphantly, greeted by a crowd of cheering smallfolk. He rides a horse towards the Red Keep with his niece on a leash behind him. In exchange for Euron's "gift" to the Iron Throne, Cersei agrees to marry him... after her enemies are defeated. Cersei then proceeds to take vengeance on Ellaria and Tyene for their part in Myrcella's murder, poisoning Tyene with the same toxin used to kill her daughter, whilst leaving Ellaria alive to watch her daughter's death, powerless to help her.
Euron's victory left Daenerys at a logistical disadvantage, as the vast majority of the ships needed to ferry her troops to mainland Westeros were lost. The capture of Ellaria and Tyene and the deaths of Obara and Nymeria Sand also left Dorne without current leadership, despite their strong opposition to the Lannisters. As a result, Daenerys must postpone her planned siege of King's Landing, at least temporarily as the bulk of her forces are still at Dragonstone. Daenerys proposes using her dragons to hunt down and burn the Iron Fleet all at once. However, Tyrion points out that Euron has likely spread out his fleet into smaller flotillas to prevent just that. Missandei also warns that the risk to Daenerys was too great, as she will be exposed and vulnerable while riding Drogon.
Daenerys and Tyrion make two other plans to gain a beachhead on the mainland: an alliance with the King in the North Jon Snow, and a separate assault on Casterly Rock, to deprive the Lannisters of their seat of power.
In the books
In the A Song of Ice and Fire books, no equivalent battle has occurred. Asha (Yara's name in the novels) is defeated and taken captive by Stannis at the Second Battle of Deepwood Motte, but the circumstances of the battle are almost totally different, for instance:
- Euron, Ellaria, the Sand Snakes, and Theon are not involved at all in the battle. The combatants are Asha and Stannis; the latter is reinforced by the Northern Mountain clans and by House Mormont.
- Asha has only four ships and 200 men.
- The battle takes place at a much earlier point of the plotline, before the Battle of Winterfell.
- The main part of the battle takes place on the mainland.
A few elements of the battle are loosely based on the taking of the Shield Islands, which occurs in the fourth novel: Victarion Greyjoy leads the Iron Fleet to attack the Shields, as the first stage of Euron's campaign against the Reach. As usual, Euron himself does not participate in the battle, only makes the plan, sends others to perform the fighting - and afterwards takes the whole credit to himself. During the battle, Victarion rams and boards one of the enemy's ships, killing many opponents with his axe; the axe gets momentarily stuck, but Victarion manages to pull it loose and keeps fighting till victory is achieved.
In "The Forsaken" sample chapter of the upcoming sixth novel, Euron expects to engage soon in a naval battle against the Redwyne fleet, but that also will happen under different circumstances, as House Redwyne remains loyal to the Iron Throne and is responding to massive raiding on the Reach's shores.
- Given that Euron's fleet had just arrived in King's Landing and departed from it to bring Cersei a gift, and that Yara had just been sent to Dorne from Dragonstone, it seems logical that Euron intercepted them in Blackwater Bay or near it. Though, it is truly uncertain, given that the Lannisters inexplicably never even bothered to capture an abandoned fortress. Further confirmation may be needed.
- "The Queen's Justice"