Question: What is the date of death of Joan Of Dampierre's mother?
Sentence (from "Margaret II, Countess of Flanders"): Margaret, often called Margaret of Constantinople (2 June 1202 – 10 February 1280), ruled as Countess of Flanders during 1244–1278 and Countess of Hainaut during 1244–1253 and 1257–1280.
Relevant evidence: Yes