In India the Russian menace seemed to necessitate the adoption of a policy towards the independent states of the North-West which brought an extension of the frontier, between 1839 and 1849, to the great mountain ranges which form the natural boundary of India in this direction; while a succession of intolerable and quite unprovoked aggressions by the Burmese led to a series of wars which resulted in the annexation of very great territories in the east and north-east: Assam, Aracan, and Tenasserim hi 1825; Pegu and Rangoon in 1853; finally, in 1885-86, the whole remainder of the Burmese Empire. In North America settlers found their way across the Rocky Mountains or over the Isthmus of Panama into the region of British Columbia, which was given a distinct colonial organisation in 1858; and the colonisation of the Red River Settlement, 1811-18, which became hi 1870 the province of Manitoba, began the development of the great central plain. In South Africa frontier wars with the Kaffirs, and the restless movements of Boer trekkers, brought about an expansion of the limits of Cape Colony, the annexation of Natal, and the temporary annexation of the Orange River Settlement and the Transvaal; but all these additions were most reluctantly accepted; the Orange River Settlement and the Transvaal soon had their independence restored, though the former, at any rate, accepted it unwillingly. In Australia, drafts of new settlers planting themselves at new points led to the organisation of six distinct colonies between 1825 and 1859; and this implied the definite annexation of the whole continent. New Zealand was annexed in 1839, but only because British traders had already established themselves in the islands, were in unhappy relations with the natives, and had to be brought under control. But it was not the territorial expansion of the British Empire which gave significance to this period in its history, but, in a far higher degree, the new principles of government which were developed during its course. The new colonial policy which gradually shaped itself during this age was so complete a departure from every precedent of the past, and represented so remarkable an experiment in imperial government, that its sources deserve a careful analysis. It was brought into being by a number of distinct factors and currents of opinion which were at work both in Britain and in the colonies.