Captured resistance members were also executed by the German authorities. Famously, Edith Cavell, a British nurse who had lived in Belgium before the war, was arrested after helping Allied soldiers to escape the country and was executed by a German firing squad in 1915. Another résistante, Gabrielle Petit, who had participated in various forms of resistance activity, was executed in 1916 at the Tir national in Schaerbeek and became a posthumous national heroine. Resistance A resistance movement developed in Belgium soon after the German occupation. Around 300 separate networks existed, often including male and female members. Resistance took various forms. Although some sabotages by the resistance, notably the destruction of the Brussels-Aachen railway line, were celebrated at the time, armed resistance represented a minority of their acts. In particular, intelligence gathering played a major role. Around 6,000 Belgian civilians were involved in gathering intelligence on German military installations and troop movements and communicating it back to the Allied armies. The organisation was run through a large number of independent groups and included, notably, the large Dame Blanche (White Lady) network. Alongside intelligence gathering were similar organisations which helped men wishing to join the Belgian Army on the Yser Front to escape occupied Belgium, usually across the Dutch border. Around 32,000 were successfully smuggled out which boosted the size of the Belgian force considerably. In addition, underground newspapers also formed a big part of resistance activity. The newspapers provided information censored in the approved press and also patriotic propaganda. Some underground papers, most notably La Libre Belgique (The Free Belgium) and De Vlaamsche Leeuw (The Flemish Lion), could reach large numbers of people. Underground newspaper were produced in a variety of formats and geographic areas, sometimes targeting specific demographics. At its height, La Libre Belgique had 600 individual contributors. The majority form of opposition, however, was passive resistance. Small patriotic badges, depicting the royal family or national colours, were extremely popular. When these symbols were banned, new ones, such as ivy leaves, were worn with similar meaning. Workers in strategic industries deliberately underperformed in their jobs as a form of resistance. The celebration of nationalist public holidays, like 21 July (National Day), which were officially banned by the Germans, were also often accompanied by protests and demonstrations. One of the most notable acts of passive resistance was the Judges' Strike of 1918, which managed to gain concessions from the German occupiers