God's verdict and the Yorkist claim to the throne
Edward and his supporters had no doubt why Edward was King. They said that God gave Edward victory because the Yorkists had the true and legtimate claim to the throne.
The signs that God favoured Edward:
1) The three suns shining at Mortimer's Cross
2) Victory at Towton
Edward also said that he had a strong legal justification for being King. In 1460 the Lords had sworn to uphold the Act of Accord (agreeing that York would inherit the throne after Henry's death). Edward said the Lancastrians had broken the Accord at Wakefield when they attacked York. At Towton God had declared against these Lancastrian oath-breakers.
We shouldn't underestimate the importance of "God's verdict" to the Yorkists because they gained a lot of support through this.
Henry VI's failure as King
Henry's failure is a vital part of the explanation for Edward's success because York would never have challenged Henry for the crown if he had been a successful King. However, Henry was not desposed simply because he was a failure. If that had been the case, he would have been deposed in 1450 during Cade's rebellion.
Simply being a bad king did not lead to deposition, so why was Henry's failure important?
The answer is that Henry's failure led to all the events and rivalries that came together at Towton to make Edward king.
1) Henry's inability to lead allowed the rivalry between Somerset and York to escalate.
2) His inability to stop feuds between nobles led to York's faining support from the Nevilles
3) These rivalries and feuds led to conflict in 1455
4) Henry's inability to provide leadership led to Margaret having to fill the vacuum as leader and ironically her decisions then played a vital part in her huband's deposition
5) This ultimately led to the battles of 1459-61.
Richard of York's persistent opposition
To depose a King there needs to be opposition and York created that. At first York said he wanted to be only the King's leading adviser but in addition, he almost certainly wanted to be seen as the king's heir.
It was this determination to be at the centre of government that seems to have alarmed Queen Margaret. Additionally, she feared York wanted to take the crown from her husband and sonm and so in 1459 Parliament passed an Act of Attainder declaring the Yorkists traitors. Attainder meant lost of all lands, and wealth and in all likelihood death. Thus, York had no real choice but to change the focus of his opposition, he was now challenging Henry's right to be king.
York's opposition therefore created the possibility for York taking the crown. However, it is clear from the Act of Accord that most nobles wanted Henry to remain king. Some fought to the death to defend him and when York was killed at Wakefield, the Yorkist caused seemed defeated.
Edward's qualities and skills
Why did York's son, Edward, succeed where York had failed?
1) He wasn't his father. York had spent ten years declaring his loyalty to Henry, only to make a dramatic about-turn in 1460, declaring that he was the rightful king. This made York look like a devious liar after all the times he'd denied accusations of treason, (not an attractive prospect as king). Edward wasn't tarnished.
2) He was everyone's image of a king: tall, well-built and handsome as well as an excellent soldier who had God's blessing. "Words fail me to relate how well the common people love and adore him, as if he were their God."
3) He was a man capable of making decisions, the central task of a king that Henry had always failed to fulfill. Edward was a real, significantly better alternative to Henry and therefore an important factor in his own success. If he had been less kingly in appearance or a poorer soldier then his chances of success would have been much smaller.
People paid a lot of attention to Edward's most powerful supporter, Richard Neville, Earl of Warwick. Warwick had played an increasingly prominent role since 1455 (his importance shown by the possible Lancastrian attempt to assasinate him in 1458). He was the most powerful and most influential nobleman in England by 1461; his lands and wealth enabling him to summon a very large number of men to fight. He control of Calais gave him both a refuge in time of difficulty, but also a shipping to mount an invasion. Warwick also had a fame and charisma that no other nobleman possessed because of his raids on foreign ships in the English channel.Ambassadors from Milan declared that Warwick "is like another Caesar in these parts" and that "everything is in Warwick's power and he had done marvellous things." Warwick's support gave credibility to Edward's claim to the throne. However, Warwick needed Edward as much as Edward needed Warwick. He was in a desperate situation, convicted of treason, close to losing everything. He had to fight on and, unable to become kinghimself, he needed someone who could. He needed Edward.
Why did Londoners slam the city gates against Margaret but open them to Edward?
1) they feared Margaret's northern army.
2) there was a historical hostility from London towards Margaret and the Lancastarians: in 1456 she had moved the royal court to the midlands (an insult to the capital and a considerable loss of trade to the city's buisnesses). Wealthy courtiers now spent their money in Coventry.
3) Many London merchants believed that the Lancastrian government favoured foreign merchants over English ones.
So Londoners believed there was a strong economic reason for opposing Lancaster, besides the fear of looting by Margaret's soldiers. They also had strong links with pro-Warwick merchants in Calais. Therefore London gave Edward men, money and credibility bceause he was proclaimed king in the capital. No other town could have given Edward so much.
The decisions of Margaret and the Lancastrians
Two decisions had consequences they didn't intend, putting Henry's hold on the throne at greater risk:
1) The first came in 1459 when Margaret called a Great council. She probably thought the Lancastrians were now strong enough to end the Yorkist threat by convicting them of treason. When the Yorkists fled from Ludford, Margaret went ahead with Acts of Attainder. This may have seemed a good tactic, showing everyone the full treachery of the Yorkists. However, the Yorkists were forced to make a choice. Either they gave in, beginning for mercy, or they fought back. If they fought, they would have no choice but to fight for the crown. So, the treason charges unintentionally made the conflict worse and increased the chances of henry's deposition. Also some nobles may have supported the Yorkists now because they felt they were being harshly and unfairly treated.
2) The second was the decision to head North rather than to advance on London. If the attack failed, this would increase Yorkist support. They were also very short of food. Lastly, London and Margaret shared a hostile relationship. They could rebuild their strength in the north and be in an eeven stronger position to defeat Edward. However, abandoning London to Edward gave Edward a much stronger chance of success.
Both these decisions were intended to crush the Yorkists but did a lot to help them.
The battle of Towton
Edward's success was not inevitable before the battle. Despite all the reasons why Edward had a chance to become king - a neutral observer would have said that he wasn't the favourite to win. There was over twice as many nobles fighting for Henry than for Edward. The weather may have worked against the Lancastrians, as the archers were at a severe disadvantage shooting into the wind and snow uphill. The late arrival of fresh Yorkist troops led by Norfolk may have galvanised the Yorkists at a critical moment.
So, why did Edward win the crown?
Edward became King because he won the battle at Towton, but why was he in a position to win the battle? Several factors gave him a chance; the support of the city of London, of Warwick, and of a handful of other nobles. Their suppport was linked to Queen's Margaret's decisions. But why was Margaret's decisions rebounded, strengthening the Yorkists instead of weakening them and giving them a chance of success. Finally, the military skills ofthe youthful, kingly Edward made the most of the chance on the battlefield.