Wars of the Roses
After the Hundred Years' War, the kings of England got into a big fight about who should be king, which caused a long civil war in England from 1455-1485 AD.
One side was the Lancaster side, which took a red rose as its symbol. The other side was the York side, which took a white rose as its symbol. Both sides were descended from King Edward III, and so both thought their guy should be king.
At the end of the war in 1485, a new family of kings took control, the Tudor (TOO-door) family, with King Henry VII. Henry VII was a very strong king, and he weakened the aristocracy so that he could stay in power. He made Parliament stronger, but not the aristocratic parliament. Henry VII worked mainly with the new lower-class part of Parliament, the House of Commons, rather than with the House of Lords.
