The other benefit is deterrence. "It will save time of fighting and will deter in many cases a potential enemy from really launching an attack."

VOA: standard.2010.07.20

Then it lands on your foot, because assuming the cannon is at zero height, the cannonball certainly comes out towards the enemy, but has no time of flight.

然后它就会落在你的脚边,因为假设大炮的高度为 0,炮弹笔直地出膛打向敌人,却没有时间飞行

耶鲁公开课 - 基础物理课程节选