In the 1850s, while studying the foreign policies of European states and endeavouring to disclose the inner springs of these policies, Marx often turned to the history of diplomacy. Working at the British Museum, he discovered, in the collection of an English historian and writer, William Coxe, a mass of eighteenth-century documents, including letters from English ambassadors in St. Petersburg. This find served as an immediate stimulus for writing the Revelations of the Diplomatic History of the 18th Century which he conceived at the beginning of 1856, when the Crimean war was still in progress. Marx wrote later: “While looking through the diplomatic manuscripts in the possession of the British Museum I came across a series of English document’s, going back from the end of the eighteenth century to the time of Peter the Great, which reveal the continuous secret collaboration between the Cabinets of London and St. Petersburg, and seem to indicate that this relationship arose at the time of Peter the Great".
