Complex sentence: In addition, many First World War veterans viewed the Russian Bolshevik armistice and treaty with Germany as a betrayal since it broke the 4 September 1914 Triple Entente agreement not to conclude a separate peace with Germany or Austria-Hungary.
Split into simpler sentences: In addition, many First World War veterans had viewed the Russian Bolshevik armistice and treaty with Germany as a betrayal. It broke the 4 September 1914 agreement between the Entente powers not to conclude a separate peace with Germany or Austria-Hungary.