The environmental impact of warfare remains a relatively understudied aspect in archaeology. Limited anthracological research has been conducted on this subject in Europe, particularly concerning modern military encampments. However, woodland resources were important to armies for building barracks or siege infrastructures, as well as for soldiers’ daily lives. This paper presents the results of charcoal analysis of two siege camps: Lanaken-Europark, located in eastern Belgium (1748: war of the Austrian Succession) and Montigny-lès-Metz “La Horgne” situated in northeastern France (1552: 10th Italian wars). The goals are to improve our understanding of the firewood supplies of modern armies at the local scale and the impact of conflicts on the landscape. The Lanaken site corresponds to the French siege of Maastricht in 1748. The study of fire pits reveals that the troops primarily sourced firewood from mature oak-dominated forest formations and nearby orchards. The results suggest that the French troops have mainly collected their firewood in the local vicinity. The site of “La Horgne” corresponds to the siege of Metz in 1552. The results show high proportions of oak and fir. However, fir groves do not occur near Metz and it is not commonly used as a fuel. Furthermore, iconography of the XVIth century does not show the presence of oak forests near Metz. These observations suggest that soldiers probably have used timber as firewood, potentially providing evidence of sacking at the end of the occupation. These results show the diversity of wood resources exploited by armies during modern conflicts. These studies are part of a doctoral project (2022-2025) which aims to better understand the management of wood resources in wartime, the impact of conflicts on the diversity of forests and to provide complementary data to historical sources.