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.
... and Heidelberg, devoting himself mainly to the doctrines of Hegel and Schleiermacher. After holding the chair of philosophy at Halle for two years, he became, in 1833, ...