- "I kill the guards. I take your two best men and lead them through the back streets, which I know well, then open the front gates. Then comes the army."
- ―Daario Naharis' plan to breach Yunkai.
Daario then assists in planning the attack on the city by informing Daenerys and her supporters of a back gate that his men use when visiting Yunkai's bedslaves. He insists that the guards know him and will let him in, at which point he will kill them. He proposes taking Daenerys' two best men, and lead them through the back streets, which he knows well. They would then open the front gates, allowing Daenerys' army to enter the city. Grey Worm trusts Daario, but Ser Jorah Mormont and Ser Barristan Selmy do not. Barristan offers to help lead the attack, but Jorah advises him to stay behind and protect Daenerys, as he is her Queensguard.
Jorah, Grey Worm and Daario reach the back gate. Daario approaches it and tells his comrades that he will signal them with a songbird's whistle. When he reaches the gate, a guard threatens him. Daario calms the guard by letting him know who he is, before killing him and another guard. He whistles, and Jorah and Grey Worm follow. Jorah informs him that there may be more guards. Daario doubts it, saying that the Yunkish prefer to let their slaves do their fighting for them. Despite this, a large group of guards surround them. After a brief skirmish, they slay the city guards, but even more appear, and surround them.
Daenerys' army later returns to her tent. Jorah informs her that the Wise Masters acted too late, and their slave soldiers threw down their spears and surrendered. Daario then approaches her with a banner which he took from the temple, places it at her feet and tells her that the city is hers.
The following morning, Daenerys addresses the city's slaves with Missandei serving as her translator. During her speech, Daenerys tells the slaves that it is their own choice to reach for their freedom. As a result, the liberated slaves revere her as their "Mhysa", which translates as "mother" from the Ghiscari language. Daenerys then mingles with the former slaves, who regards her as a "glimmer of hope" in an increasingly dark world.
Since Daenerys moves on from Yunkai to Meereen and decides to rule over the city, the Wise Masters manage to return to power and enslave all the freedmen who remained in the city.. In response, Daenerys sends to Yunkai a Great Master of Meereen at her service, Hizdahr zo Loraq, in order to negotiate with the Wise Masters: if they do not comply with her demands of abandoning slavery once and for all, Daario Naharis will send in his Second Sons and execute them all.
In the books
In the A Song of Ice and Fire books, the Battle of Yunkai takes place in a quite different manner. Yunkai has hired both the Second Sons - led by Mero - and the Stormcrows - led by Prendahl na Ghezn, Sallor the Bald, and Daario Naharis. Daario turns over the Stormcrows to Daenerys after murdering both Prendahl and Sallor. With the Stormcrows on her side, Daenerys orders an attack against the unsuspecting Second Sons, who are getting drunk on a wagon of wine given to them by Daenerys. While her Unsullied and Dothraki attack the Yunkish slave defenders from the front, Daario's Stormcrows take them in the rear. Almost 200 Yunkish infantry are killed while the rest surrender while the Second Sons also suffer minimal casualties and yield nonetheless. Mero, however, escapes.
The TV version does have Daenerys gift a barrel of strong wine to the Second Sons, apparently a nod to this subplot in the books.
Without the sellsword companies to protect Yunkai, the Wise Masters have no choice but to surrender. They comply to Daenerys' demands: all the slaves are freed and are allowed to take from their former masters all the weapons, food, money and merchandise as they can carry. Yunkai is otherwise unharmed. The Wise Masters are allowed to remained in control of the city. Daenerys does not leave an armed force in Yunkai in order to prevent the Wise Masters from stirring up troubles, and that proves to be a serious mistake.
Although the Yunkai'i have been deprived of their slaves and much of their property, they remain wealthy. Soon after Daenerys' host leaves to Meereen, they start to plot against her. After the Siege of Meereen ends, a messenger from Astapor informs Daenerys that new levies have been raised and can be seen drilling outside the city walls, warships are being built, envoys have been sent to New Ghis and Volantis to make alliances and hire sellswords. The Yunkai'i have even dispatched riders to Vaes Dothrak to bring a khalasar down upon Daenerys. Daenerys is greatly disheartened by these news, but takes no action against Yunkai.