As a result of the Wars of the Three Kingdoms, many in both Scotland and England viewed standing armies as a threat to individual liberty and society itself. Those who wanted a military career joined units in foreign service, such as the Dutch Scots Brigade; loyalties were often based on religion or personal relationships, with officers moving between armies. Douglas' younger brother John (1647–1675) was killed at Trier with the French army, while Robert (1650-1676) died serving with the Dutch at Maastricht.