Trivia question

[AussieMick]

What issue caused the following to be written ...

"We would respectfully remind you of the object lesson afforded by the United States at the conclusion of their Civil War. The leaders of the South were entirely in the power of the North. Many of them were officers and officials who had sworn allegiance to the laws of the United States and had afterwards taken up arms and inflicted enormous losses upon her. None the less not one of these men was executed, and this policy of mercy was attended by such happy results that a breach which seemed to be irreparable has now been happily sealed over.”

Googling ? I've tested it and I dont think its going to help, but you can try.

Some hints might be needed.