Good finding. Very good one indeed.

[link to en.wikipedia.org]

Catherine of Valois (27 October 1401 – 3 January 1437[1]) was the Queen consort of England from 1420 until 1422. She was the daughter of Charles VI of France, wife of Henry V of England,[2] mother of Henry VI of England, and through her secret marriage with Owen Tudor, the grandmother of Henry VII of England.[3] Catherine's older sister Isabella was queen of England from 1396 until 1399, as the child bride of Richard II.

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Henry V went to war with France, and even after the great English victory at Agincourt, plans for the marriage continued. Catherine was said to be very attractive and when Henry finally met her at Meulan, he became enamoured. In May 1420, a peace treaty was made between England and France, and Charles acknowledged Henry of England as his heir. Catherine and Henry were married at the Parish Church of St John or at Troyes Cathedral on 2 June 1420. Catherine went to England with her new husband and was crowned queen in Westminster Abbey on 23 February 1421. In June 1421, Henry returned to France to continue his military campaigns.

I read in the French wiki page that the dowry of Catherine of Valois was...the Aquitaine and Normandy duchies!!

In addition, this marriage with Henry V of England was sealed thanks to the Treaty of TROYES:

[link to en.wikipedia.org]

The Treaty of Troyes was an agreement that Henry V of England and his heirs would inherit the throne of France upon the death of King Charles VI of France. It was signed in the French city of Troyes on 21 May 1420 in the aftermath of the Battle of Agincourt. It forms a part of the backdrop of the latter phase of the Hundred Years' War, in which various English kings tried to establish their claims to the French throne.

Hence the Great Monarch of the prophecies supposed to be French, but will be English!!