Condon will play Dwight D. Eisenhowers trusted aide Captain Kay Summersby.
The complex decision-making was critical in the fate of WWII and the course of history.
Additional casting is underway, with Studiocanal handling world sales.
Kerry Condon, Andrew Scott And Brendan FraserCourtesy/Getty Images/Chad Griffith
The film will concentrate on the pressure cooker of the decision-making but also capture the scale of the landings.
The wrong conditions could devastate the largest-ever seaborne invasion, while any delay risks German intelligence catching on.
Better Call Saulactress Condon is coming off acclaim for Martin McDonaghsTheBanshees Of Inisherin.
