unsiege
/ˌʌnˈsɪdʒ/Definitions
1. verb
to relieve a besieged place or people from the pressure or attack of an enemy.
“The arrival of reinforcements unsieged the city after months of siege.”
2. noun
the act of relieving a besieged place or people from the pressure or attack of an enemy.
“The unsiege of the city was a turning point in the war.”