The preliminary bases of peace between Russia and Turkey were signed at Adrianople (Jan. 31) on the terms summarised above, except that the Czar's Ministers now withdrew the obnoxious clause about the Straits. A line of demarcation was also agreed on between the hostile forces; it passed from Derkos, a lake near the Black Sea, to the north of Constantinople, in a southerly direction by the banks of the Karasou stream as far as the Sea of Marmora. This gave to the Russians the lines of Tchekmedje, the chief natural defence of Constantinople, and they occupied this position on February 6. This fact was reported by Mr. Layard, Sir Henry Elliot's successor at Constantinople, in alarmist terms, and it had the effect of stilling the opposition at Westminster to the vote of credit. Though official assurances of a reassuring kind came from Prince Gortchakoff at St. Petersburg, the British Ministry on February 7 ordered a part of the Mediterranean fleet to enter the Sea of Marmora for the defence of British interests and the protection of British subjects at Constantinople. The Czar's Government thereupon declared that if the British fleet steamed up the Bosporus, Russian troops would enter Constantinople for the protection of the Christian population. This rivalry in philanthropic zeal was not pushed to its logical issue, war. The British fleet stopped short of the Bosporus, but within sight of the Russian lines. True, these were pushed eastwards slightly beyond the limits agreed on with the Turks; but an arrangement was arrived at between Lord Derby and Prince Gortchakoff (Feb. 19) that the Russians would not occupy the lines of Bulair close to Constantinople, or the Peninsula of Gallipoli commanding the Dardanelles, provided that British forces were not landed in that important strait[160]. So matters rested, both sides regarding each other with the sullenness of impotent wrath. As Bismarck said, a war would have been a fight between an elephant and a whale. [Footnote 160: Hertslet, iv. p. 2670.] The situation was further complicated by an invasion of Thessaly by the Greeks (Feb. 3); but they were withdrawn at once on the urgent remonstrance of the Powers, coupled with a promise that the claims of Greece would be favourably considered at the general peace[161]. [Footnote 161: L. Sergeant, _Greece in the Nineteenth Century_ (1897), ch. xi.]