In August 1941, after the establishment of the Axis-aligned Independent State of Croatia, by Party decision Zlatić was sent to the Kordun region to help provide medical care to Partisan troops. The medical field work proved to be very risky, as it involved hours of traveling on foot to reach the wounded, crossing guarded roads and railway tracks in the process. This led to a decision to build an improvised hospital in the Partisan-controlled area of Petrova Gora mountain. The hospital, co-founded by Zlatić, became operative in October 1941. After it was discovered and destroyed by enemy forces, it was rebuilt in a different location on Petrova Gora. The new hospital remained undetected for the duration of the war, treating more than 5,000 patients. Apart from general medical work in the hospital, Zlatić also performed minor surgery.