On the other flank of the Czar's dominion--his hereditary enemy, the Grand Seignior, was at this time actually at war with him. Napoleon had neglected his relations with Constantinople for some years past; but he now perceived the importance of keeping this quarrel alive, and employed his agents to stimulate the Grand Seignior to take the field in person at the head of 100,000 men, for the purpose of co-operating with himself in a general invasion of the Russian empire. But here he encountered a new and an unforeseen difficulty. Lord Castlereagh, the English minister for foreign affairs, succeeded in convincing the Porte, that, if Russia were once subdued, there would remain no power in Europe capable of shielding her against the universal ambition of Napoleon. And wisely considering this prospective danger as immeasurably more important than any immediate advantage which she could possibly reap from the humiliation of her old rival, the Porte commenced a negotiation, which, exactly at the most critical moment (as we shall see hereafter) ended in a peace with Russia. The whole forces of Italy--Switzerland, Bavaria, and the princes of the Rhenish League,--including the Elector of Saxony,--were at Napoleon's disposal. Denmark hated England too much to have leisure for fear of him. Prussia, surrounded and studded with French garrisons, was more than ever hostile to France; and the king was willing, in spite of all that he had suffered, to throw himself at once into the arms of Russia. But this must have inferred his immediate and total ruin, unless the Czar chose to march at once into Germany. Such a movement was wholly inconsistent with the plan of operations contemplated, in case of a war with Buonaparte, by the military advisers of Alexander; and Frederick William saw himself compelled to place 20,000 troops, the poor relics of his army, at the disposal of the common oppressor.