Final answer:
The subject matter involves various historical events and battles, particularly the Battle of Yorktown, the pivotal and final major conflict in the American Revolution, and the War of the Roses, the series of civil wars for English throne control, indicating a focus on significant historical military conflicts.
Step-by-step explanation:
The phrase 'Richard Of York Gave Battle In Vain' is often used as a mnemonic to remember the colors of the rainbow in the order of red, orange, yellow, green, blue, indigo, and violet. However, based on the numerous references provided, the underlying subject of the question seems to be associated with historical battles and conflicts. These range from individual acts of valor during battles, like the story of Doffue Martling, to significant historic events such as the Battle of Crécy, the War of the Roses, the Hundred Years' War, and the Battle of Yorktown during the American Revolution.
Among these events, the Battle of Yorktown is particularly notable as it marked the last major action of the American Revolution, culminating in the surrender of General Cornwallis's army on October 19, 1781. The siege effectively ended British efforts to suppress the revolution and led to the eventual recognition of American independence. The War of the Roses, another prominent conflict mentioned, was a series of civil wars for control of the throne of England fought between two rival branches of the royal House of Plantagenet: the House of Lancaster (associated with a red rose) and the House of York (white rose), culminating in the rise of the Tudor dynasty.