While the ambassadors were drinking the young king asked them what was the thing they most feared, thinking, says the historian, that they would say himself, but their answer was quite different. "We fear no one," they said; "there is only one thing that we fear, which is, that the heavens may fall upon us; but the friendship of such a man as you we value more than everything," whereat the king, no doubt considerably astonished, remarked in a low voice to his courtiers what a vainglorious people these Celts were.[16]
All through the life of Alexander the Celts and Macedonians continued on good terms, and amongst the many envoys who came to Babylon to salute the youthful conqueror of Persia, appeared their representatives also. Some forty years later, however, this good understanding came to an end, and the Celts overthrew and slew in battle the Macedonian ruler Ptolemy Keraunos about 280 B.C.
With the Romans, as with the Greeks, the relations of the Celts were, during the fifth and fourth century B.C., upon the whole friendly, and their hostility to the Etruscans must have tended naturally to render them and the Romans mutual allies. The battle of Allia, fought on the 18th of July, 390 B.C., and the storming of Rome three days later, were a punishment inflicted on the Romans by the Celts in their exasperation at seeing the Roman ambassadors, contrary to the right of nations, assisting their enemies the Etruscans under the walls of Clusium, but these events appear to have been followed by a long peace.[17]
It is only in the third century B.C. that the hitherto victorious and widely-colonising Celts appear to have laid aside their internal political unity and to have lost their hitherto victorious tactics. The Germans, over whom they had for centuries domineered and whom they had deprived of their independence, rise against them about 300 B.C., and drive out their former conquerors from between the Rhine and the Black Sea, from between the Elbe and the Maine. The Celts fall out with the Romans and are beaten at Sentinum in 295 B.C.; they ally themselves with their former enemies the Etruscans, and are again beaten in 283 B.C. and lose territory. They cease their alliance with the Greeks, and are guilty of the shameful folly of pillaging the temple of Delphi, an act of brigandage from which no good results could come, and from which no acquisition of territory resulted. They established a colony in Asia Minor in 278 B.C., successfully indeed, but absolutely cut off from the rest of the Celtic Empire, and such as in any federation of the Celtic tribes could only be a source of weakness. Again, about the same time, we see Celts driving out and supplanting Celts in the districts between the Rhine, the Seine, and the Marne. In 262 B.C. we find a body of three or four thousand Celts assisting their former foes the Carthaginians at the siege of Agrigentum, where they perish. Many of the Celts now took foreign service. It was at their instigation that the war of mercenaries broke out, which at one time brought Carthage to the very verge of destruction.