 In 1941/42 he served as commander of Infantry Regiment 737 in Serbia, where he was promoted to lieutenant colonel in December 1941.During this period he was ordered to undertake mass shootings in reprisal for partisan activity, but later stated that he never carried out such orders (though officers in nearby zones clearly did).As of 1 May 1942, Wildermuth was commander of Infantry Regiment 371 at Army Group Center on the Eastern Front and then from May 1943 as commander of Infantry Regiment 578 in Italy.