One of the sources of George Martin’s Game of Thrones was apparently the English dynastic conflicts known as the Wars of the Roses. Lasting from 1455 to 1485, the Wars of the Roses were a series of battles between the Houses of York and Lancaster (Stark and Lannister?) over who would ultimately possess the English throne.
For all practical purposes, the WoR ended on August 22, 1485 when the Lancaster pretender, Henry Tudor (afterwards Henry VII) defeated and killed the York king, Richard III, at the Battle of Bosworth (Henry VII and his son Henry VIII continued to kill off York family members for years after Bosworth, but organized resistance was pretty much over). Interestingly, Henry VII officially announced that his reign began on August 21, 1485, the day before Bosworth. This meant that instead of fighting for their legitimate King, Richard, all his supporters were fighting against legitimate King, Henry, making them traitors and subject to loss of lands, titles and lives.
Critics and fans of GoT talk often refer to Danerys Targeryan’s mission as the “invasion” or the “conquest” of Westeros. They also chronicle her “descent into madness.” They point to the execution of the Tarlys, and of Varys, as clear signs of this madness, which attains its ultimate expression in the destruction of King’s Landing. I would argue, though, that this point of view doesn’t take into account what Dany really believes—she is the rightful ruler of the Seven Kingdoms, and her opponents are traitors.
We have to get out of our modern mindset, and view Dany’s story arc in the terms of medieval royal politics. There are no democracies in Westeros, no “consent of the governed.” There is a King, or Queen, and the only question is who that person will be. Kings govern by right, either by right of birth/succession, or by right of conquest (this was how Henry VII characterized his own right to rule). The Targeryan dynasty had ruled Westeros for 300 years, and after the death of Aerys II, the Mad King, his heir would be the rightful king. Since most of the Targeryans were killed, with only Viserys and Dany surviving, Viserys was the rightful King, and after his death, Dany was the rightful Queen (Jon Snow’s parentage was unknown until well into the series).
In Dany’s eyes, Robert Baratheon was never the legitimate King, nor were his Lannister successors (although at least Robert could claim he was King by right of conquest). And she does not view herself as merely one of the many pretenders or players in GoT. Robert, Joffrey, Tommen, Renly, Stannis, Robb Stark—none had any claim to the throne. Rather, they were traitors, conspiring to take her throne. They were traitors, and their lands and lives were forfeit. So, for instance, when Dany offers to spare the Tarlys, and let them keep their lands and titles, with only the condition that they swear fealty to her (“bend the knee”), she’s being remarkably generous. When they refused, they got the sentence they deserved.
But what about the destruction of King’s Landing? Traditionally, a city which surrenders before any armed resistance was spared. Once they resisted, however, the city was sacked and its inhabitants killed or sold into slavery. This is how the Romans did it, this is how the Mongols did it, this is how the Crusaders did it, and this is how it was done in medieval Europe.
Obviously, the slaughter of innocents in KL goes too far for me—I’m a believer in just war theory, and in modern (i.e., post Renaissance) terms, the inhabitants of KL should have been spared once the city surrendered. And clearly GoT doesn’t play entirely by the old rules, since Jon, Tyrion and Varys all think it’s wrong to reduce KL to ashes. But during much of human, and apparently Westerosi, history, what happened to KL was normal. As Marlon Brando said to Matthew Broderick in The Freshman, “that’s how it’s done.”