The siege of Thimert (1058–60) was the last military action in the war between King Henry I of France and Duke William the Bastard of Normandy.
In the first half of 1058, William captured the French fortress at Thimert in the County of Dreux.
[3] By 23 May 1059, when Henry's son Philip was consecrated as joint king with his father, negotiations for a truce had been opened.
King Henry sent Bishops Humbert of Paris and Guy of Amiens to seek terms in Normandy.
Around the same time, Duke William and many of his leading men were in Dreux, only about twelve miles from Thimert.