From 1455 to 1485 England was wracked by the horrors of Civil War, kings were made, deposed, reinstated, deposed again and out righted murdered in the quest for control of the throne.
The followers of the House of the Duke of Lancaster were those of the Red Rose.
While the followers of the House of the Duke of York choose the White Rose.
For a time, the powerful Richard Neville, 16th Earl of Warwick earned the title of "Kingmaker" during this war as he threw his support to different contenders. At first he supported the Lancasterian Henry VI (king from:1422-1461 and 1470-1471), then helped Edward IV of York (king from: 1461-1470 and 1471-1483) to the throne, after a falling out with Edward, he helped to put Henry VI back on the throne. Before he could change sides again he was killed in the Battle of Barnet in 1471, leaving Edward IV as king.
With the death of Edward IV, his young son Edward was proclaimed king, with his Uncle Richard, Duke of Gloucester as "Lord Protector" of the boy king. The murder of Edward V (13 years old) and his younger brother Richard, Duke of York in 1483, left their Uncle Richard as the sole surviving adult male of the line and therefore king (there was an 8 year old nephew, Edward, son of Richard's executed younger brother George. Edward himself would be beheaded in 1499).
Richard III (1483-1485) was unpopular, thought to be the murderer of Edward V and a usurper. It did not take long for his enemies to form an army and challenge him for the crown.