This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Q: John met the rebel leaders at Runnymede, near Windsor Castle, on 15 June 1215. Langton's efforts at mediation created a charter capturing the proposed peace agreement; it was later renamed Magna Carta, or "Great Charter". The charter went beyond simply addressing specific baronial complaints, and formed a wider proposal for political reform, albeit one focusing on the rights of free men, not serfs and unfree labour. It promised the protection of church rights, protection from illegal imprisonment, access to swift justice, new taxation only with baronial consent and limitations on scutage and other feudal payments. A council of twenty-five barons would be created to monitor and ensure John's future adherence to the charter, whilst the rebel army would stand down and London would be surrendered to the king.
A:
When did John meet the rebel leaders at Runnymede?