John, King of England
The king returned west but is said to have lost a significant part of his baggage train along the way. Roger of Wendover provides the most graphic account of this, suggesting that the king's belongings, including the Crown Jewels, were lost as he crossed one of the tidal estuaries which empties into the Wash, being sucked in by quicksand and whirlpools. Accounts of the incident vary considerably between the various chroniclers and the exact location of the incident has never been confirmed; the losses may have involved only a few of his pack-horses. Modern historians assert that by October 1216 John faced a "stalemate", "a military situation uncompromised by defeat".
When were the Crown Jewels lost?
as he crossed one of the tidal estuaries
Roger of Wendover provides the most graphic account of this, suggesting that the king's belongings, including the Crown Jewels, were lost as he crossed one of the tidal estuaries which empties into the Wash, being sucked in by quicksand and whirlpools.
the Crown Jewels