Negotiations were opened between the holed-up Peter and his besieger, Henry.
From the en.wikipedia.org
When they did, they often found that a determined besieger had got there before them.
From the time.com
If all else failed, a besieger could claim the booty of his conquest undamaged, and retain his men and equipment intact, for the price of a well-placed bribe to a disgruntled gate-keeper.
From the en.wikipedia.org
More examples
An enemy who lays siege to your position
An energetic petitioner
(Besiegers) A siege is a military blockade of a city or fortress with the intent of conquering by attrition or assault. The term derives from sedere, Latin for "to sit". ...