If it weren't truly impossible for her to leave, Mrs. Tang would have long wanted to go to the border.
Young Master Su and the other three are really too mischievous. If Mrs. Tang went to the border, she would definitely take Young Master Su along.
There's no playmates in the military camp, not even enough tents to dismantle every day for his amusement; Marquis Dongxiang wouldn't need to fight battles, hitting his son daily would be enough.
The camp is so large, it's inevitable spies may infiltrate. While it's difficult to kidnap others, Young Master Su, however intelligent, is still young. He is Marquis Dongxiang's only flesh and blood. Mrs. Tang endured much suffering to give birth to him back then; how could she bear to let him risk danger?
Knowing Marquis Dongxiang's temperament, if Young Master Su were captured by Nanliang, it's really uncertain he'd be rescued.
