I think you have confused it a bit too much, it was just about 'using diplomacy as a tool of war' or 'using diplomacy to create balance of power' or 'achieving national interest through diplomacy'
.
You could quote examples such as Congress of Vienna which aimed at creating a balance of power in Europe to prevent wars. Or you could quote the example of United Nations where big powers show their muscle to each other and determine their share over global power without actively engaging in war with each other etc
. Or you could quote from early Islam when Prophet Muhammad (SAW) attempted to create balance of power in Medina by means of a messaq(-e-madina) and treaties etc.
Or the way China is rising as a regional and global power is also an example of nations winning without fighting. China is asserting itself in the region by just 'showing' its military capabilities and using its economic influence. It also engages Western powers diplomatically who are feeling rise of a mighty nation and its growing influence without actually proving it by means of combat
.