After so much about the political, I think it's high time for a post of the personal, so here are the children of Richard Duke of York and his wife Cecily Neville:
1. Anne, who married the Duke of Exeter. Exeter was York's ward but nevertheless a substantial dowry was paid. Nonetheless the marriage was not a success at either a political or personal level. Exeter became one of York's worst enemies (though he was pretty much the enemy of everyone) and eventually Anne divorced him and married Sir Thomas St.Leger. Exeter conveniently fell overboard on the way back from the French expedition of 1475, having spent several previous years in the Tower. Sir Thomas St. Leger was executed by Richard III.
2. Henry (died young).
3. Edward, Earl of March (later Edward IV).
4. Edmund, Earl of Rutland. Killed at Wakefield 1460.
5. Elizabeth, who married John de la Pole, Duke of Suffolk. This marriage forged an alliance with the de la Pole clan, previously enemies of York. Suffolk was a political nonentity but there were numerous children. The males in particular had a hard time under the Tudors and were eventually wiped out.
6. Margaret, who married Charles Duke of Burgundy. No children, but Duchess Margaret was a relatively major player in European politics.
7. William (died young)
8. John (died young)
9. George, Duke of Clarence. Executed/judicially murdered 1478.
10. Thomas (died young)
11. Richard, Duke of Gloucester (later Richard III).
12. Ursula (died young.)
One interesting and unexplained feature of the Yorks' marriage is the several years** that passed before Anne was born. Clearly the problem was not one of fertility as they eventually had 12 children! It may be that York's absence at the French wars is part of the answer but it's not a complete one as Cecily was often there with him. (For example Edward and Edmund were born in Normandy.)
** Marriage 'before October 1429' (source P A Johnson) Anne's birth 1439.
One internet source states there was another daughter Joan b 1438, but this child is not recorded in the famous ballad about York's offspring printed in Caroline Halstead's Richard III.
The Wiki article on Cecily Neville says that the couple were not 'officially married' (whatever that means) until 1437. I'm inclined to doubt this.