Since August 11, 2015, The International Institute of Social History (IISH) in Amsterdam has made its archive containing letters, manuscripts, publications, and other papers from Karl Marx and Friedrich Engels available for free online. All of the documents have been digitized over the last three years. They can be found under the Karl Marx/ Friedrich Engels Papers in the IISH catalogue.
The physical archive measures 5.6 meters (approximately 18.5 linear feet) of shelf space. Among other things, it houses the first edition of Marx’s magnum opus, Capital (Volume I), which contains his handwritten notes for a subsequent edition, as well as a handwritten page from The Communist Manifesto.
The aforementioned documents were inscribed on UNESCO’s Memory of the World Register in June 2013. The archive also contains letters Marx wrote to the Philips family, Dutch industrialists to whom he was related and who he frequently asked for money. Letters written by his wife, Jenny Marx-von Westphalen, are also included in it.
The IISH was established in 1935, and purchased the Marx and Engels archive in 1938 for 72,000 guilders (equivalent to approximately 640,000 euros – or $736,000 – today). At that time, the institute and its predecessors, such as the Netherlands Economic History Archive, were important repositories for personal papers and documents written by social thinkers who were persecuted elsewhere in Europe.
The Marx-Engels archive originally belonged to the Social Democratic Party of Germany (SPD), which put it up for sale when it could no longer be kept safely in Germany under Hitler. The specialized Marx-Engels-Lenin Institute in Russia also sought to acquire the archive, but its representatives were ordered back to Moscow by Stalin in the middle of the negotiations and ultimately executed.
The archive did not arrive in Amsterdam until 1946, after being safeguarded in England during the German occupation. With great foresight, an alternate location was established for it there just before the war.