Because the manpower potential of the Republic's territory was so limited, the States-General had to look beyond Dutch borders for a large part of the recruits. Fortunately, in those days foreign authorities did often not object to recruitment efforts within their territories (at least before the beginning of the Thirty Years' War when recruitment possibilities in Germany became more limited). The Republic therefore was able to obtain large numbers of recruits from Scotland, England, the Holy Roman Empire, France, and later also the Protestant Swiss Cantons (with whom special treaties were made for this purpose). Other than the Army of Flanders the Dutch States Army kept these foreign contingents separate in their own regiments. This had the advantage that in case of threatened mutiny one contingent could be checked by the others. The army leadership also often exploited the rivalry between these "Nations" to extract extra efforts, for instance by organizing "races" between contingents of sappers of different nationality for the first trench to reach the ditch of a besieged fortress, as happened during the Siege of Breda (1637). The downside of this policy was that sometimes epic brawls erupted between the contingents