The word "besieges" means to surround or blockade a city, building or enemy force. The antonym for this word could be "liberate" which means to free from confinement, oppression or control, allowing freedom of movement. Another antonym for "besieges" could be "release" which means to set free from imprisonment, captivation or restraint. Alternatively, the word "abandon" can be used as an antonym for "besieges", signifying to relinquish control, leave or desert an area. Other possible antonyms can include "protect," "guard," or "defend" which mean to safeguard or shield something or someone from harm.