You’ve cited Edward of Lancaster before as a proto-Joffrey. May I ask why? Yes, he’s described as having been enthusiastic about war (the ‘lalks of nothing but making war’ thing), but that’s a far cry from Joffrey’s brand of indiscriminate sadism, isn’t it?

Here are the similarities:

Disputed paternity: Yorkists alleged for a long time that the combination of Henry VI’s notorious piety on matters of the flesh and his repeated mental breakdowns meant that Marguerite d’Anjou had slept with one of her court favorites (either the Duke of Somerset or the Earl of Ormonde) to conceive an heir after eight years with no issue.
Violent tendencies: Edward was more than a bit enthusiastic about war; in addition to talking about war, he also “talks of nothing but of cutting off heads,” and “delighted in attacking and assaulting the young companions attending him,” although it’s a bit ambiguous whether that was referring to military training. What’s not ambiguous is that, after the Second Battle of St. Albans, Edward ordered that the two Yorkist knights who had been guarding his father be decapitated, despite the fact that they had voluntarily stayed on the field to protect his father and had honorably surrendered. He was also reportedly a big fan of the decapitation and spiking of the Duke of York, his son the Earl of Rutland, and the Earl of Salisbury after Wakefield, so the beheading thing was a bit of a common thread.
Engaged to the enemy: Edward of Lancaster was married to Anne Neville, the younger daughter of the Earl of Warwick, who had been one of the chief supporters of the Yorkist cause and the opposing general at the Second Battle of Albans, for example.
Similar rival: Just as Joffrey was enraged at the victories of Robb Stark the Young Wolf, Edward of Lancaster’s main opponent was the young Edward IV, who similar to Robb Stark was always victorious when he was commanding but who was undone when he broke his betrothal and made an impulsive marriage.

Is Daeron II’s claim to the throne purely de facto? Once Daemon is legitimate, his claim through his mother should precede Daeron’s being the elder son of their father, right? How would such a claim compare to that of the Mortimers vs. the House of Lancaster? If Daemon’s original bastard status still counts, what is the point of legitimization? Why were the Beauforts legitimized if they were excepted from the royal succession?

Let’s say for the sake of argument that, for some reason, a Great Council had been called in 184 to settle the succession. How would the various claims stack out?

Primogeniture: clearly favors Daeron, who was born in 153 AC, whereas Daemon was born in 170 AC. (Among the other Great Bastards, Aegor was born in 172, and Bloodraven in 175). This is one of the reasons why the Blackfyres had to allege that Daeron “Falseborn” was not Aegon IV’s son – if they’re both legitimate, Daeron clearly comes first.
Proximity: now this might favor Daemon. Both men are sons of Aegon IV, but Daeron is the son of Naerys (daughter of Viserys II), and Daemon is the son of Daena (daughter of Aegon III). Since Aegon III came first, that would indicate that Daemon’s claim might be superior. (On the other hand, just as when the Lancastrians pointed to the recency of Henry V and Henry IV as opposed to the Yorkists going back to the sons of Edward III, this could be a contested issue). However, since the Great Council of 101 declared the female line irrelevant for succession purposes, this would probably be a wash.

As to the Wars of the Roses: I would say that Daemon’s claim would be a good bit more proximate than the Mortimer claim, since Edmund Mortimer was the great-grandson of Edward III’s second son Lionel of Antwerp (through the female line) and was only heir presumptive when Richard II was deposed, and by the time you get to Henry VI vs. Richard Duke of York you’ve got a lot of interposing kings. At the same time, the Yorkists also pointed to the direct male claim through Edward III’s fourth son Edmund of Langley.

As for the Beaufort claim, I talked about it here and here.

Besides carrying the standard, would a standard bearer typically have any other duties?

The standard bearer’s primary role is to motivate and help direct the troops by showing them which direction they were to go and where they should rally to in the confusion of battle – thus why standard-bearers were chosen from among the strongest and bravest, to make sure that they would be right at the front of every charge and would never abandon their position even in the most dire situation, which in turn would ensure that the soldiers looking to them for guidance would not go astray.

In the Middle Ages, it was also common for standard-bearers to act as bodyguards for the lords and kings whose banners they held. For example, at the Battle of Bosworth Field, when Richard III made his suicidal cavalry charge intending to kill Henry Tudor, Sir William Brandon (Henry’s standard-bearer) placed himself in between Richard and his prey and was slain by the king, saving Henry’s life. Equally impressively, Richard III’s standard-bearer, Sir Percival Thirlwall, kept the Yorkist banner flying even after losing both of his legs.

Could English kings actually just legitimize bastards, like in Westeros?

Yes, they could! Although it gets really really weird, in the best dynastic scholarship way.

So, let’s talk English inheritance law! In Saxon England, all sons of a King were titled as “aethelings” and were eligible to inherit regardless of their legitimacy. The Papacy was not a huge fan of this, being rather a big proponent of the idea that Christian marriages should be important to monarchs and future monarchs, and tried to outlaw the practice, not always successfully. King Aethelstan (924-939) was a bastard, as was William of Normandy. But gradually succession through legitimate union took hold, sort of…

For a while, you had something of a mixed case, where royal bastards were given the last name of Fitzroy (son of the king) and wore royal coat of arms marked with a bend or bar to distinguish them – as we see above. Especially in the reign of Henry I, there were about 21-25 Fitzroys running around who were very very powerful people with Earldoms and Dukedoms, and while they weren’t guaranteed a place in line, they could sometimes have one. Robert Fitzroy Earl of Gloucester was a potential claimant for the English throne during the Anarchy, although he ultimately ended up backing Empress Maude over King Stephen instead.

You then scoot down to one of the weirder bits of dynastic tomfoolery that took place during the Wars of the Roses, and how it is that the Tudors wound up with a claim on the English throne. John of Gaunt, richest and most hated of the sons of Edward III, had a bunch of children with his mistress Katherine Swynford and then married her. The ex-facto results of this union were declared legitimate repeatedly by Kings, Parliament, and Popes, as quid-pro-quo for supporting Richard II, although the condition of legitimacy was that they had to give up their claims to the succession.

When Henry IV usurped the throne from Richard II, and was feeling insecure on his throne, he recinded the titles that had been given to the Beauforts through their legitimation, as a symbolic underlining of the situation, and got the succession re-ordered in Parliament – although to keep them sweet, the Beauforts were given the lands of Owen Glendower, which is where the first Welsh connection comes in. A bit later, Henry VI didn’t have much in the way of close relatives, he did something very odd: he legitimated the Welsh House of Tudors, who decended from his mother’s second marriage to Sir Owen Tudor, in 1452, and then in 1455 married Margaret Beaufort to Edmund Tudor, linking the two families

The dynastic chaos of all of this seemed to have left an enduring lesson after the Wars of the Roses. While there would be powerful royal bastards – Henry VIII’s son Henry Fitzroy Duke of Richmond and Somerset, Charles II’s bastard James Fitzroy the Duke of Monmouth – they would never be added to the succession, even if it meant enduring the occasional rebellion (see Monmouth’s Rebellion).

Do you believe that there was English revanchism after they began to lose most of there lands in France that led up to the invasion of Edward the third?

To quote Wolf Hall:

“I hope he doesn’t think still of invading France.”

“God damn you! What Englishman does not! We own France. We have to take back our own…Mind you, you’re right…We can’t win,” the duke says, “but we have to fight as if we can. Hang the expense. Hang the waste – money, men, horses, ships. That’s what’s wrong with Wolsey, see. Always at the treaty table. How can a butcher’s son understand-”

“La gloire?”

So yes, if you look at English politics from the 15th century on, there was a good deal of revanchism. A good deal of the Wars of the Roses began as a split between the peace faction of the Duke of Somerset, his brother the Cardinal, and the Duke of Suffolk, and the war party of Richard Duke of York and Humphrey Duke of Gloucester, who blamed Suffolk and Somerset’s military incompetence for the loss of much of England’s territories in France.

And you see the same tensions outlasting the Hundred Years War. When Edward IV went into exile in 1470, he went to Burgundy which had been England’s ally against France and where the Duke was Edward’s brother-in-law. Burgundy gave Edward the cash he needed to return to England when France declared war on Burgundy, making a friendly Yorkist king in England a useful check on French aggression. (Meanwhile France was a major supporter of the Lancastrian claim, due to their links to Marguerite d’Anjou.)

In 1475, Edward IV actually went to war with France and landed in Calais with 16,000 troops, but when Burgundy failed to follow through with military support, the French paid him 75,000 crowns plus a yearly pension of 50,000 crowns to forgo his claim to France and abandon Burgundy. Charles the Bold died two years later at the Battle of Nancy, leading to the collapse of the independent duchy of Burgundy and its incorporation into France.

Richard III hadn’t been a huge fan of Edward IV’s deal with France, going so far as to refuse the pension that France had agreed to pay him, especially when France renewed its Auld Alliance with Scotland to keep the English busy, leading to war with Scotland in 1480. Richard’s well-known anti-French sympathies led the French government to provide troops to Henry Tudor to overthrow him.

Henry VII repaid his French assistance with some rather spectacular double-dealing. When France supported Perkin Warbeck the imposter in a bid to keep England divided, Henry invaded Brittany. On the other hand, he was happy to be bought off with the French dropping Warbeck and giving him 742,000 crowns, even if this meant betraying Britanny, since he didn’t really care about regaining England’s lands in France. On a third hand, he allied himself with Spain and signed a peace deal with Scotland (in both cases through dynastic marriages) in an effort to isolate France. His more romantic son Henry VIII was very much interested in regaining England’s lands in France, and went to war with France in 1512, 1513, 1521, and 1544.

Note that the Kings of England maintained their claim to the French throne until 1i902.