The hospital was built near Ostrožno Brdo, a village in the hills inland from the Slovenian coast. It was set up by Magomed Gadzhiev, a doctor from Dagestan. Born into a family of doctors, Gadzhiev had deserted from a pro-German military force into which he had been drafted and joined the Slovenian resistance. With most of the valley regions occupied by the Nazis, Gadzhiev and his team set up the hospital in the Brkini hill country.

During its existence, the hospital treated more than 200 people, mostly wounded soldiers. Its facilities had enough space for 22 patients, while a nearby bunker featured a rudimentary operating room. Zalesje was short of medical equipment, and sometimes, even garden implements, including saws, were used during surgery. Despite this, it had the lowest mortality rate of any field hospital in Slovenia. Some patients could not be brought to the hospital; Gadzhiev frequently rode his horse from village to village to treat both wounded soldiers and residents of the area.

The hospital was ultimately discovered – and partially destroyed – by the Germans who saw smoke coming out from its kitchen, but most of the staff and the patients were safely evacuated.

The hospital remained a source of local pride. For years, only a small memorial served as a reminder of Zalesje. Recently, two of the hospital buildings were renovated and a museum devoted to the hospital was set up in a nearby school.

After the war, Gadzhiev returned to his native Dagestan, where he established himself as a highly respected doctor. His son and his grandson continued the family tradition by becoming leading doctors in Slovenia, while his descendants in Dagestan also practice medicine.