But when Athens saw the Peloponnesian confederacy again established, and as she could not, on account of the truce, attack it directly, she looked to the colonial law, which rested rather on hereditary feelings than on positive institution, for an opportunity of an indirect attack. This was soon found in the defensive treaty with Corcyra, which state was engaged with its mother country Corinth in a war, according to ancient Greek principles, wholly unlawful and unjust. Besides this, however, it was an actual breach of the thirty years’ truce.(842) And the same principles were expressed in the demand that Potidæa should, for the sake of the Athenian confederacy, give up its original connexion with the parent state. In both these cases it is manifest that the maxims of the Athenian policy were directly at variance with the general feeling of justice entertained by the Greeks, and especially with the respect for affinity of blood; and this fundamental difference was the true cause of the Peloponnesian war. 13. As it would not be consistent with the plan of this work to give a detailed account of the influence of the Peloponnesian war upon the political and private character of the Greeks, we must be content to point out the following obvious points of opposition between the contending parties. In the first place, then, _Dorians were opposed to Ionians_; and hence in the well-known oracle it was called the Doric war.(843) The individual exceptions are for the most part merely apparent;(844) also when the Athenians attacked Sicily, all the Doric cities were opposed to them.(845) On the side of Athens were ranged all the Ionians of Europe, of the islands, and of Asia, not indeed voluntarily, but still not altogether against their inclination. _The union of the free Greeks against the evil ambition of one state._ At the beginning of the war the general voice of Greece was in favour of Sparta(846) (which was heard through the Delphian oracle, when it promised that state assistance);(847) nor did she compel any one to join in it. The allies of Athens, having previously been Persian subjects, were accustomed to obey; and on the present occasion forced to submit; the public assembly of Athens was the only free voice in so large a combination. _Land-forces against sea-forces._ According to the speech of Pericles, Peloponnesus was able, in an action with heavy-armed troops, to resist all the rest of Greece together; and Athens avoided coming to this mode of engagement with singular ingenuity. The fleet of the Peloponnesians, on the other hand, was at the beginning of the war very inconsiderable.(848) Hence it was some time before the belligerent parties even so much as encountered one another. The land was the means of communication for one party, the sea for the other: hence the states friendly to Athens were immediately compelled to build _long walls_ for the purpose of connecting the chief city with the sea, and isolating it