Before the Germans requisition the St. Joseph Foundation on the former estate 'Hohenheim', the complex functions as a nursing institution for Roman Catholic 'mental patients' who reside here and - if possible - also work. It is given the name 'Kriegslazarett 4/686' and is one of the two official 'Kriegslazarette' in Gelderland, alongside the one in Arnhem. Unlike other German emergency hospitals, surgical procedures are also performed here.

After the failed liberation operation Operation Market Garden in September 1944, wounded British paratroopers are initially cared for in the improvised Airborne Military Hospital in the Koning Willem III barracks in Apeldoorn. When they are later taken as prisoners of war to German camps, the remaining wounded are transferred to the Kriegslazarett on Deventerstraat. British Major Simon M. Frazer from a medical unit of the British Army is allowed to stay to care for the wounded - he demanded this from the German leadership. He does this together with five nurses from the same unit: Fred Budd, Geoffrey Owen, Norman Mawditt, Phil Jackson, and Parker.

Dutch civilians are also treated in the Kriegslazarett. Resistance fighter Johannes Arnoldus (Jan) van Bijnen - alias Frank - from Oosterhout is seriously wounded on November 29, 1944, during a liberation action by resistance members from the Willem III barracks in a firefight with the Germans. He dies shortly thereafter on December 1, 1944, from his injuries. American co-pilot Ned Benedict threatens to crash his fully loaded bomber into buildings in Wormerveer, North Holland, on February 14, 1945, but manages to crash it into the fields. Ned and two of his crew members are treated for their (burn) wounds at the Kriegslazarett in Apeldoorn. Ned experiences the liberation in April 1945.

One of the patients is the Austrian Hanns Albin Rauter, head of the SS and the police force in the Netherlands. South of Apeldoorn, near the hamlet of Woeste Hoeve, the car in which Rauter is traveling is riddled with two hundred bullets on the night of March 6, 1945. His driver and adjutant are killed, but Rauter himself survives the mistaken attack. He is admitted to the Kriegslazarett the next morning at nine o'clock with severe injuries and receives two liters of blood, which saves his life. As a reprisal measure, 263 men are executed a day later, 117 of them at Woeste Hoeve.

On April 13, 1945, the Canadians liberate the hospital after neutralizing two German snipers. They find 789 patients, including Canadians who were wounded in previous battles in Roermond and the German city of Kleve. An Allied officer lines up the German medical staff neatly in front of the building and hands over the officers and nurses to the Canadians. Soon, approximately nine hundred civilians come to the complex to seek shelter from the war and to have their wounds treated. On April 14, the hospital becomes a command post for the Canadians for a number of days because Villa Laag Buurlo has been hit by a German grenade. On April 28, wounded Allied soldiers are transported to the United Kingdom.