chéng rén bù bèi
to take advantage of sb in an unguarded moment (idiom)
to take sb by surprise
chū qí bù yì gōng qí bù bèi
catch an enemy off guard with a surprise attack (idiom, from Sunzi's Art of War 孫子兵法|孙子兵法)
chū qí bù yì , gōng qí bù bèi
to catch an enemy off guard with a surprise attack (idiom, from Sunzi's "The Art of War" 孫子兵法|孙子兵法[Sun1 zi3 Bing1 fa3])
gōng qí bù bèi
see 出其不意,攻其不備|出其不意,攻其不备[chu1 qi2 bu4 yi4 , gong1 qi2 bu4 bei4]