As Nazi Germany successfully attacked country after country, resistance movements all over Europe emerged to combat the enemy. Resistance included many activities. The Belgian resistance developed numerous "escape lines" and helped liberate Belgium. The Netherlands had massive worker strikes. In France, resistance members altered shipping manifests, changed labels on cargo, and continually mixed up the German supply lines. Denmark successfully saved most of its Jewish population. Although resistance movements were similar, the types of activities varied and were unique to each country. Historians have sometimes overlooked resistance as a component of warfare, for these movements are confusing and usually difficult to document. Frequently, resistance operations have many components, each person plays only a small role and the stories of average men and women go untold. Those who played larger roles had their stories told after the war, but sometimes these stories turned into books of hero worship, not accurate biographies. Some government documents are still classified, and the story of resistance is still subject to political manipulation and myth making. In addition, because of the clandestine nature of underground movements, some events were never recorded. Unlike information from other government branches, documentation of resistance movements was discouraged, especially by the underground in occupied countries, for fear that it would fall into the enemy's hands. When historians do locate information, names have often been changed or multiple aliases used. All of these elements make evidence on resistance difficult to find and to use.