Meri voluntarily joined the Red Army in 1940 while the Molotov-Ribbentrop Pact was still in force. After Nazi Germany attacked in June 1941, His corps retreated to the Porhov region, he was wounded four times during the battle while serving as a platoon commander in north-west Russia in 1941. In August 1941 he was awarded a Gold Star of the Hero of the Soviet Union for organizing the defense of the headquarters of the 22nd Estonian Territorial Rifle Corps when the German army broke through the lines near Dno in July 1941. In reality the defense was commanded by captain Arnold Isotamm, but he was not deemed to be suitable for the decoration, as he was not a member of the Communist Party and had been an officer of the Estonian Army. Meri was specifically commended for remaining on the battlefield despite being wounded four times. Meri retired from the Red Army as a colonel. The building that housed the headquarters of the 22nd Estonian Rifle Corps in July 1941 is currently occupied by a secondary school. In 2008 the school was renamed in honour of Arnold Meri.