A serious conflict occurred between Henry Julius and the Brunswick citizens, when they refused to recognize his overlordship. Henry Julius was not willing to confirm the city's traditional privileges and had mercenary ("Landsknecht") troops deployed, leading to a civil war in 1605. Attempts by King Christian IV of Denmark to mediate failed and in 1606, Emperor Rudolf II banned the city. In 1607, Henry Julius again went to the emperor's court, in order to negotiate the details of the ban. In return, he was given the emperor's full support in dealing with the Brunswick insurgents. Nevertheless, all attacks on the city failed.