A Parliament had been summoned, (to meet at Coventry in November) to which the Yorkist lords were not invited. This in itself suggests it was intended to attaint them there.
There was now a period of what might be called negotiation. The Yorkist lords rejected pardons - because they did not see themselves of having offended - but on the other hand they took a solemn oath in front of Garter King of Arms at the high altar of Worcester Cathedral that they were loyal to the King. They also sent a letter to the King via Garter that explained their position. In a nutshell they argued that Henry's supporters were incompetent and wanted to seize their lands and offices. Therefore they were not able to come into the King's presence except under the protection of an armed force.
From their point of view this attitude was understandable, but it did not cut much ice with Henry and would have allowed their opponents (the Queen, Somerset et. al.) to cast serious doubt on their good faith.
From Worcester they moved to Tewkesbury (very much on Warwick's Beauchamp/Despenser territory) but then retreated to Ludlow. The pattern of movement suggests they were trying to break out - perhaps to the London/Kent area where they had significant support - but found themselves outmanoeuvred by the Lancastrian forces.
The strategy was presumably to negotiate from behind strong defences, or if necessary fight. However the position of the Yorkists was quite desperate, and the King was marching against them with a very substantial army. Resistance was treason, at least if they were defeated. Defeat was quite likely, given the odds against, and, although the leadership allegedly made rallying speeches, there was an undoubted collapse of morale.
The King had offered a general pardon, still in force at this point (October 1459) and many of the Yorkist rank-and-file decided to defect and accept it. The best known of these is Sir Andrew Trollope who took with him most, if not all, of Warwick's force from the Calais garrison. However it appears other soldiers may have gone as well. This was not heroic behaviour, but it was understandable in the circumstances.
The position at Ludlow was now untenable, and York, his two elder sons (the earls of March and Rutland), Salisbury and Warwick slipped out of the back door and into Wales, leaving Duchess Cecily with her younger sons (George and Richard) and any daughters who were at home (Margaret?) to stand famously at the market cross of Ludlow and beg for mercy and protection. This was granted to them but the town, not being noble, was sacked. Many other prominent Yorkist supporters (including the future William, Lord Hastings) were granted pardon, though in some cases this was for life only in the first instance.