The story
A reference to Richard of York, 3rd Duke of York (1411–1460), who was killed in the Battle of Wakefield.
Etymology from Wiktionary, CC BY-SA 4.0.
Richard of York gave battle in vain
Today it means: A mnemonic phrase to help remember the order of the seven colours of the rainbow: red, orange, yellow, green, blue, indigo, violet. Full definition →