There's a popular story in Russia about the Cossacks writing an insulting letter to the Sultan of the Ottoman Empire. They had been asked to capitulate and promise allegiance to the Ottoman Sultan and replied with a parody of an official document with various titles and honorifics replaced with Vulgar insults. Although the letter may be apocryphal (only one copy of it was found - by a poet in the 1870s) it coincided with a period of intense raiding by the Zaphorozhian Cossacks into Ottoman territory so if it existed you could say it played a role in international conflict!

More importantly it played a part in defining Russian nationalism in the late 1800s. Although they'd been an often oppressed minority for hundreds of years Cossacks were coming to be romanticized as something uniquely Russian. They represented a devil may care attitude, a love of freedom and a pragmatic attitude to life with a healthy disrespect for authority.

You can read a translation of the letter on wikipedia. http://en.wikipedia.org/wiki/Reply_of_the_Zaporozhian_Cossacks#Context

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