While Stadler was commander of the "Der Führer", a subordinate unit under his command committed the Oradour-sur-Glane massacre. On 10 June 1944, part of the regiment, led by SS-Sturmbannführer Adolf Diekmann, killed 642 inhabitants of Oradour-sur-Glane. Stadler he ordered a court martial for Diekmann; the latter was killed in action before he could face the ordered trial.