A prolonged battle is a conflict that lasts for an extended period of time. In this case, the term is being used to describe a SIEGE, which is a military tactic where an attacking force surrounds a defended location in order to isolate it and reduce its ability to resupply or communicate with the outside world. A SIEGE can last for days, weeks, months, or even years, depending on the strength of the defending forces and the resources available to the attackers.