Complex sentence: It is important to note that the average citizen of the Netherlands was unaware of the operation of "death camps" such as Mauthausen for the majority of the occupation, as all Dutch citizens were obligated to "register" and undertake work in Germany.
Split into simpler sentences: It is important to note that the average citizen of the Netherlands was unaware of the operation of "death camps" such as Mauthausen for the majority of the occupation. As all Dutch citizens where obligated to "register" and undertake work in Germany.