But meantime the Continental Celts had either--as Jubainville seems to think--recovered their faculty for pronouncing _p_, or else--as Rhys believes--been overrun by other semi-Celts who, owing to some strong non-Aryan intermixture, found _q_ repugnant to them, and changed it into _p_. This appears to have taken place prior to the year 500 B.C., for it was at about this time that they, having established themselves round the Seine and Loire and north of the Garonne, overran Spain, carrying everywhere with them this comparatively newly adopted _p_, as we can see by their tribal and place-names. They appeared in Italy sometime about 400 B.C.,[9] founded their colony in Galatia about 279 B.C., and afterwards sent another swarm into Great Britain, and to all these places they bore with them this obtrusive letter in place of the primitive _q_, the Irish alone resisting it, for the Irish represented a first off-shoot from the cradle of the race, an off-shoot which had left it at a time when _q_ represented _p_, and not _p q_. Hence it is that Welsh is so full of the _p_ sound which the primitive Irish would never adopt, as a glance at some of the commonest words in both languages will show.
English: Son tree head person worm feather everyone. Welsh: Ma_p_ _p_renn _p_en ne_p_ _p_ryv _p_luv _p_au_p_. Irish: Ma_c_ _c_rann _c_enn ne_ch_ _c_ruiv _c_luv[10] _c_á_ch_.
So that even the Irish St. Ciaran becomes Piaran in Wales.[11]
The Celts invaded Italy about the year 400 B.C., and stormed Rome a few years later. They were at this time at the height of their power. From about the year 500 to 300 B.C. they appear to have possessed a very high degree of political unity, to have been led by a single king,[12] and to have followed with signal success a wise and consistent external policy. The most important events in their history during this period were the three successful wars which they waged--first against the Carthaginians, out of whose hands they wrested the peninsula of Spain; secondly in Italy against the Etruscans, which ended in their making themselves masters of the north of that country; and thirdly against the Illyrians along the Danube. All of these wars were followed by large accessions of territory. One of the most striking features of their external policy during this period was their close alliance with the Greeks, whose commercial rivalry with the Phœnicians naturally brought them into relations with the Celtic enemies of Carthaginian power in Spain, relations from which they reaped much advantage, since the necessity of making head against the Celtic invaders of Spain must have seriously crippled the Carthaginian power, at the very time when, as ally of the Persians, she attacked the Greeks in Sicily, and lost the battle of Himera on the same day that the Persians lost that of Salamis. Greek writers of the fourth century speak of the Celts as practising justice, of having nearly the same manners and customs as the Greeks, and they notice their hospitality to Grecian strangers.[13] Their war with the Etruscans in North Italy completed the ruin of an hereditary enemy of the Greeks,[14] and their war with the Illyrians no doubt largely strengthened the hands of Philip, the father of Alexander the Great, and enabled him to throw off the tribute which the Illyrians had imposed upon Macedonia. Nor did Alexander himself embark upon his expedition into Asia without having first assured himself of the friendship of the Celts. He received their ambassadors with cordiality, called them his friends, and received from them a promise of alliance. "If we fulfil not our engagement," said they, "may the sky falling upon us crush us, may the earth opening swallow us up, may the sea overflowing its borders drown us," and we may well believe that these were the very words used by the Celtic chieftains when we find in an Irish saga committed to writing about the seventh century[15] the Ulster heroes swearing to their king when he wished to leave his wing of the battle to repel the attacks of a rival, and saying, "heaven is over us and earth is under us and sea is round about us, and unless the firmament fall with its star-showers upon the face of the earth, or unless the earth be destroyed by earthquake, or unless the ridgy, blue-bordered sea come over the expanse (?) of life, we shall not give one inch of ground."