A siege is a prolonged military assault and blockade[?] on a city or fortress[?] with the intent of conquering by force or attrition[?].
Sieges usually involve surrounding the target and blocking the provision of supplies.
... for arranging clandestine air operations in northern France.
Ceux de la Resistance[?]
Ceux de la Liberation[?]
Chantiers de la Jeunesse[?] or "youth camps" - ...