When the war started going badly for Romania as the autumn of 1916 wore on, the ministry was involved in organizing resistance to German-led occupation, destroying the petroleum infrastructure, sinking grain deposits in the Danube and sending the Romanian Treasure to Moscow. When the army began retreating into Moldavia, Morțun was blamed for his handling of the material evacuation, in particular of the grain supply. He was also criticized for not working ahead of time to create an informants' network in potentially occupied areas. He exited the government right after the Battle of Bucharest resulted in the capital falling to the Central Powers and the national leadership moving to Iași. During his subsequent time as Assembly president, he oversaw the June 1917 adoption of reforms to the Constitution, providing for electoral and land reform, and the April 1918 ratification of the union of Bessarabia with Romania. He owned an estate in Broșteni, Neamț County, outside Roman; during the 1907 peasants' revolt, a mob of some 400 peasants destroyed the house of its Jewish leaseholder. Morțun himself, who lived to see much of his estate expropriated, died in Broșteni in 1919, and was buried on the premises.