Both sides were locked in a cycle of violence and vengeance. 双方陷入暴力和复仇的循环之中。

take/wreak/inflict vengeance on sb He was desperate to take vengeance on Marie’ s killer. 他不顾一切，一心想向杀害玛丽的凶手复仇。

The disease came back with a vengeance. 这种疾病又爆发了，来势凶猛。