Reply of the Zaporozhian Cossacks to Sultan Mehmed IV of the Ottoman Empire, also known as Cossacks of Saporog Are Drafting a Manifesto, oil on canvas (1891) by Ilya Repin. The Cossacks writing a letter to Mehmed IV in 1676. The Cossacks defeated the Ottoman Turkish forces in battle in 1676, but the Sultan wanted them to submit to Turkish rule, and (as the legend goes) the Cossacks wrote an insulting letter in reply.