Following the 1916 Treaty with the Entente, King Ferdinand I and Premier Brătianu agreed to join the war against the Central Powers. This had the effect of silencing Germanophile dissidence. Alexandrina volunteered for work as a nurse. In August 1916, she became manager of the No. 113 Hospital, set up at the SONFR Institute in Bucharest with funds from the National Bank of Romania (her assistant managers were Elena Odobescu and Elena Perticari). By the end of the year, however, the Romanian Army was on the retreat everywhere, with the Germans in sight of Bucharest. King and government followed the Army retreat into Moldavia, where they remained besieged until 1918. The invasion further divided the Cantacuzino family, between those who aligned themselves with the German regime in Bucharest, and those who, as loyalists, fought against the Germans in Moldavia. The Zamora Castle was requisitioned by the Imperial German Army, serving as residence for the Governor, August von Mackensen.