On 1 March 1942, the school was requisitioned by the German Ortskommandantur. After the German withdrawal, the building served as headquarters for General William Simpson, commander of the Ninth US Army, from 22 October 1944 to 10 March 1945.

The Allied commanders on the Western Front, Dwight Eisenhower (US), Bernard Montgomery (UK), Omar Bradley (US) and Arthur Tedder (UK), all arrived at Simpson on 7 December 1944 for deliberations. The central question was how to bring Hitler to his knees. The airborne landings near Arnhem had failed, and the Allied advance was stalled everywhere. Eisenhower and Montgomery were diametrically opposed when it came to the strategy to be followed: advance over a broad front (Eisenhower) or penetrate quickly and deeply towards the Ruhr region and Berlin (Montgomery). The outcome is not known. Presumably, the two met somewhere in the middle, but daring airborne landings far behind the frontline as at Arnhem and Nijmegen were a thing of the past.

Simpson hosted a high-level visit again in March 1945, this time from the British Prime Minister Winston Churchill. The school building was largely demolished in the mid-1990s, but the façade was retained. The gate made by artist Hans Lemmen from stones from the river Meuse not only reminds us of the war, it also depicts the heads of pupils entering and leaving through the gate.