In the second part of 1916, as Romania joined the war on the side of the Entente, Călin was drafted as a combat medic, and was later assigned to the military ambulance. Retreating to Moldavia along with the whole Romanian Army, he contracted typhus during the epidemic that ravaged the region during the war. Transported to Iaşi for treatment, he died there in early April 1917. Over one thousand workers and socialists were present on at his burial, which became the first major socialist public gathering in Romania after the start of the war. The manifestation, and especially the anti-war eulogy given by Bujor, which called on the Romanian workers to follow the example of the anti-monarchic revolution in Russia, resulted in a major crack-down by the authorities on the renascent socialist movement in Moldavia.