Shortly before the outbreak of World War I Farnana was living in Belgium. When Belgium was invaded by Germany in 1914, Farnana enlisted in the Belgian Army. He served with the Korps der Congolese Vrijwilligers (Congolese Volunteers Corps) during the Siege of Namur. On 23 August 1914 he was taken prisoner in Liège and deported to Germany where he spent the remainder of the war. After his release, he founded an association known as the to advocate for the interests of other Congolese veterans of the war.