What day of the week was September 21, 1217?

The day of the week September 21st, 1217 fell on was a Thursday.

Lembitu the Estonian military leader died on this day in 1217. As did Caupo of Turaida .

Livonian Crusade: The Estonian leader Lembitu and Livonian leader Kaupo the Accursed are killed in Battle of Matthew's Day.