of the time in the same way as the introduction of gunpowder affected the warfare of the Middle Ages.
The tall, round- or broad-headed Celts described in the last chapter, composing the van of the great Aryan army, ultimately destined to rule the west, brought with them the knowledge of bronze into Britain, and are proved to have conquered nearly every part of the British Isles, by their tombs scattered over the face of the country, alike in England, Scotland, Wales, and Ireland. The conquered peoples survived probably in a state of slavery, and were only preserved from absorption in the west,—where farther retreat was forbidden by the waters of the ocean. They are proved, however, by the human skulls discovered in the Heathery Burn cave near Durham, in association with bronze articles, to have been living in north-eastern Yorkshire during the late Bronze age; during the time that the swords and spears, and other articles mentioned in the following list, were in use. Thus the Celtic conquest of Gaul was repeated in Britain, with precisely the same ethnical results (see Figs. 112, 113), the only difference being that the conquest of the one took place in the Neolithic age, while the conquest of the other spread the civilisation of the Bronze age over regions where it had hitherto been unknown.
The introduction of bronze into the other countries of Europe is not marked by an invasion like that of Britain. In Scandinavia the Neolithic inhabitants acquired the bronze civilisation without any evidence of the appearance of a new people, and in Switzerland and France the Neolithic stage of culture passed away without any break in the ethnical continuity. Nevertheless, for the reasons given above, the new weapons would necessarily
