The civil war in House of the Dragons Targaryen will be divided between those loyal to the greens or blacks led by the queen and the princess.
The world of House of the Dragon would quickly be divided between the green and black factions of Targaryen allegiance who would play a significant role in the series even before the Civil War. Instead of depicting a larger war waged by many kings as in Game of Thrones the House of the Dragon conflict was primarily driven by disputes within the House Targaryen family tree that had simmered for some time before. the death of King Viserys. Since the lords of Westeros would have to pawn their swords on one of the Targaryens claims to the throne the entire realm would be divided between those who supported the Greens and those who supported the Blacks.
The most important event in the House of the Dragon is the Dance of the Dragons in which Rhaenyra Targaryen and Aegon II Targaryen will fight for the Iron Throne after the death of their father. As the eldest of King Viserys Is children Rhaenyra has long been considered his heir to the throne though her uncle Daemon felt that he was her rightful heir. However once Viserys remarried and eventually gave birth to a son the succession to the throne became more complicated.
As Viserys claimed that Rhaenyra would be his heir Aegon IIs mother Alicent Hightower grandfather Otto Hightower and several other lords conspired to give him the throne thus beginning the Targaryen Civil War in the House of the Dragon. The war which lasted about three years plunged Westeros into one of the most devastating conflicts in history especially considering that it was one of the only cases where the two warring parties managed to gain access to the dragons.
Unlike the War of the Five Kings in Game of Thrones the Civil War in the House of the Dragon Civil War would be easier to follow in terms of the allegiances of the major houses like the Starks Tullys Lannisters and Baratheons. With only two sides to choose from entrusting swords to blacks or greens often involved more dealings arrangements or personal loyalties. Since all families were already supposed to be loyal to House Targaryens it was simply a matter of figuring out which Targaryens had the best claim or offering them the best odds. While Dance of the Dragons will mark the exact moment the kingdom officially split down the middle Westerosis allegiances to the Greens and Blacks had been growing for many years before that.
Why is the Targaryen Civil War divided between Greens and Blacks?
The House of Dragons by Alicent Hightower and Rhaenyra Targaryen The greens and blacks of the Targaryen Civil War refer to the house colors of Alicent Hightower and Rhaenyra Targaryen. Once Aliscent of Viserys married Rhaenyras father a feud arose between them primarily once the kings young wife bore him a male heir. In the 111th AC main competition at Kings Landing Alicent wore House Hightower green while Rhaenyra wore House Targaryen black and red.
Later those who sided with the Queen were called the Greens while those who supported the Princess were called the Blacks. House of the Dragons Greens and Blacks originally referred to the Queens Party and Princess Party but has been associated with Aliscents son Aegon II Targaryens claim against the Rhinera claim. As such the Targaryen Civil War between Aegon and Rhaenyra was separated by the Green Party and the Black Party though it primarily concerned Rhaenyra and Alicents feud at court.
Rhinera Targaryen and Aliscent Hightower explain the long way
Hotd Young Rhaenyra & Alicent While Rhaenyra Emma DArcy and Alicent Olivia Cooke would quickly become enemies in House of the Dragon Season 1 the two began their bond on friendly terms. Aliscents father Otto Hightower was the hand of the king for both Gehaerys I and his successor Physeris I meaning young Rainera Melli Alcock and young Aliscent Emily Carey spent a lot of time together at court being the first only nine years younger. than the latter. However while the two still enjoyed a relatively friendly relationship after Aliscents marriage to Viserys of House of the Dragon the children she bore him continued to underestimate the strength of Rhineras claim to the throne. Since Viserys decided that Rhaenyra was the rightful heir to the Iron Throne he stood by.