He was Russian correspondent of "The Daily Telegraph" from 1887 to 1914 and, for a short time, was professor of Sanskrit, Classical Armenian, and Comparative Philology at the University of Kharkiv. He was a friend and associate of the Russian statesman Sergei Witte, whom he accompanied in 1905 to the peace conference at Portsmouth, New Hampshire which formally brought to an end the Russo-Japanese War. He also reported the Dreyfus trial of 1899, the Boxer Rebellion in 1900, and the Versailles peace conference in 1919. When working as a journalist, Dillon occasionally disguised himself in order to observe the action from closer quarters, as was the case when he was sent by "The Daily Telegraph" to report on the Turkish massacres of Armenians in 1894-1895.