In occupied Belgium and France, citizens opposed the German army with organized but non-violent resistance. They created networks dedicated to military intelligence gathering, escape lines, clandestine postal networks and underground newspapers. Many of the networks were dismantled by the German secret police but those executed for their resistance became national heroes.
Debruyne, E. (2016). Resistance (Belgium and France). In Ute Daniel, Peter Gatrell, Oliver Janz, Heather Jones, Jennifer Keene, Alan Kramer, and Bill Nasson (ed.), 1914-1918-online. International Encyclopedia of the First World War. Freie Universität Berlin. https://doi.org/10.15463/ie1418.10943