###If the border is in a natural place for a border then you shouldn't need to patrol it all that much.

Long term stable borders tend to be along mountain ranges, rivers, across seas and deserts etc. Places where an army naturally comes to a halt and moving further is a serious bit of logistics. The borders of Britain, Italy, and Spain for example.

On the other hand the borders of somewhere like France or Belgium have shown themselves not to be so stable over the past century or so. The European plain is a wonderful territory for marching an army and everyone from Napoleon to Hitler have tried it.

So if you've drawn your border down a mountain range with limited passes, then all you need to do is watch the passes and keep half an eye over the rest of the range but you don't need to man the whole thing.

If the border is in a natural place for a border then you shouldn't need to patrol it all that much.

Long term stable borders tend to be along mountain ranges, rivers, across seas and deserts etc. Places where an army naturally comes to a halt and moving further is a serious bit of logistics. The borders of Britain, Italy, and Spain for example.

On the other hand the borders of somewhere like France or Belgium have shown themselves not to be so stable over the past century or so. The European plain is a wonderful territory for marching an army and everyone from Napoleon to Hitler have tried it.

So if you've drawn your border down a mountain range with limited passes, then all you need to do is watch the passes and keep half an eye over the rest of the range but you don't need to man the whole thing.