How did Schliemann’s excavation methods damage parts of the Troy site?

Heinrich Schliemann’s excavations at Hisarlik were driven by a single-minded desire to uncover the Homeric Troy. Because he believed this city existed in the lowest level of the mound, he dug uncritically through the upper layers to reach it.1

In his haste, Schliemann damaged and destroyed significant portions of other settlement layers. By failing to properly document or preserve the stratigraphy of the site, his methods resulted in the loss of valuable archaeological evidence. It was not until his later work with the architect Wilhelm Dörpfeld that more systematic and efficient techniques were introduced, which finally allowed for a clearer understanding of the site's complex history.1