A British soldier of Swiss descent, Basil Eugster attended Beaumont College. In 1935 he joined the Irish Guards. He served with his regiment through the Second World War and fought in the Narvik Campaign in Norway in 1940. He was Commanding Officer of the 3rd Battalion Irish Guards in 1945, and again in 1947, and of the 1st Battalion Irish Guards from 1951 to 1954.