He opened negotiations with General Dearborn, and arranged local armistices. Cold War tensions, however, remained strong during the 1950s even after the 1953 Korean Armistices. Armistices and instruments of surrender are intended to achieve a "modus vivendi". That prisoner was held in North Korea for eighteen months and repatriated after the armistices. Austria and Hungary signed separate armistices following the overthrow of the Habsburg Monarchy. Armistices with the Central Powers were signed later that year. However, successful ceasefires may be followed by armistices and then by peace treaties. Previous armistices had been agreed with Bulgaria, the Ottoman Empire and the Austro-Hungarian Empire. Both armistices came into effect at thirty-five minutes past midnight (0035 hours) on 25 June.