Diplomacy

Free to read here, from Project Gutenberg.

To Herat and Cabul: A Story of the First Afghan War

G. A. Henty

On the manner of negotiating with princes

Monsieur de Callières

Inconstancy

Roger D. Aycock

Crisis!

C. M. Kornbluth

Gravy Train

Daniel F. Galouye

Secret Diplomacy: How Far Can It Be Eliminated?

Paul S. Reinsch

World in a Mirror

Albert Teichner