verb · to switch one's political or organizational loyalty and join the opposing side

他原本是組織的核心人物，卻在危急時刻選擇向對手投誠。

verb · to lay down arms and capitulate to an enemy force, typically involving a change of allegiance to the opposing side

敵軍見大勢已去，紛紛放下武器向我軍投誠。