In OTL, upon Margaret of Anjou and Edward of Lancaster's arrival in England, they began a march to Wales, where Jasper Tudor had raised an army of 5,000 men. Margaret's army soon found itself in a race to reach Wales, before the Yorkist army headed by Edward IV could catch them. They attempted to cross into Wales by using the bridge at Gloucester, but the Mayor denied them access to the town, as per Edward IV's orders. They then tried to cross into Wales at Upton-on-Severn a few miles north, but were forced to give battle to the Yorkists and were later defeated in the disastrous Battle of Tewkesbury.
But what if the Lancastrians had had a bit more luck and where able to cross into Wales? Maybe they are allowed enter Gloucester and enter Wales from there, or are able to reach Upton-on-Severn, before the Yorkists can catch them. Either way, the Lancastrians are in Wales before Edward IV can catch them, and are about to meet up with Jasper's force. What happens now? Does Edward IV wait for reinforcements, or does he pursue them into Wales, and fights a Battle against them a few days later?
But what if the Lancastrians had had a bit more luck and where able to cross into Wales? Maybe they are allowed enter Gloucester and enter Wales from there, or are able to reach Upton-on-Severn, before the Yorkists can catch them. Either way, the Lancastrians are in Wales before Edward IV can catch them, and are about to meet up with Jasper's force. What happens now? Does Edward IV wait for reinforcements, or does he pursue them into Wales, and fights a Battle against them a few days later?