Question

Why were military prisons during the Civil War not constructed very well?

Answer 1

Both sides believed the war would be short lived, so little attention was paid to prisons.

Answer 2

Neither side thought the war would last very long.

Step-by-step explanation:

This was a basic strategical error based on an uncertain premise. This premise, which both sides seemed to have adopted as truthful, was that the war was not going to be very long, therefore those prisons would quickly fall in desuse, making the prisons unnecessary and unworthy of being well constructed because of it.