The ambitious Czar Nicholas looked upon Turkey as his destined prey, and waited with impatience a sufficient excuse to send his armies again to the Balkan Peninsula, whose mountain barrier formed the great natural bulwark of Turkey in the north. Though the Turkish government at this time avoided direct oppression of its Christian subjects, the fanatical Mohammedans were difficult to restrain, and the robbery and murder of Christians was of common occurrence. A source of hostility at length arose from the question of protecting these ill-treated peoples. By favor of old treaties the czar claimed a certain right to protect the Christians of the Greek faith. France assumed a similar protectorate over the Roman Catholics of Palestine, but the greater number of Greek Christians in the Holy Land, and the powerful support of the czar, gave those the advantage in the frequent quarrels which arose in Jerusalem between the pilgrims from the East and the West. [=The Balance of Power in Europe=] Nicholas, instigated by his advantage in this quarter, determined to declare himself the protector of all the Christians in the Turkish Empire, a claim which the sultan dared not admit if he wished to hold control over his Mohammedan subjects. War was in the air, and England and France, resolute to preserve the "balance of power," sent their fleets to the Dardanelles as useful lookers-on. [=The Sultan Declares War Against Russia=] The sultan had already rejected the Russian demand, and Nicholas lost no time in sending an army, led by Prince Gortchakoff, with orders to cross the Pruth and take possession of the Turkish provinces on the Danube. The gauntlet had been thrown down. War was inevitable. The English newspapers demanded of their government a vigorous policy. The old Turkish party in Constantinople was equally urgent in its demand for hostilities. At length, on October 4, 1853, the sultan declared war against Russia unless the Danubian principalities were at once evacuated. Instead of doing so, Nicholas ordered his generals to invade the Balkan territory, and on the other hand France and England entered into alliance with the Porte and sent their fleets to the Bosporus. Shortly afterwards the Russian Admiral Nachimoff surprised a Turkish squadron in the harbor of Sinope, attacked it, and--though the Turks fought with the greatest courage--the fleet was destroyed and nearly the whole of its crews were slain. This turned the tide in England and France, which declared war in March, 1854, while Prussia and Austria maintained a waiting attitude. No event of special importance took place early in the war. In April Lord Raglan, with an English army of 20,000 men, landed in Turkey and the siege of the Russian city of Odessa was begun. Meanwhile the Russians, who had crossed the Danube, found it advisable to retreat and withdraw across the Pruth, on a threat of hostilities from Austria and Prussia unless the principalities were evacuated.