They crossed the Danube in June. In a month later they had occupied the principal passes of the Balkan mountains and were in position to descend on the broad plain that led to Constantinople. But at this point in their career they met with a serious check. Osman Pasha, the single Turkish commander of ability that the war developed, occupied the town of Plevna with such forces as he could gather, fortified it as strongly as possible, and from behind its walls defied the Russians. [=Osman Pacha and the Defence of Plevna=] They dared not advance and leave this stronghold in their rear. For five months all the power of Russia and the skill of its generals were held in check by this brave man and his few followers, until Europe and America alike looked on with admiration at his remarkable defence, in view of which the cause of the war was almost forgotten. The Russian general Krüdener was repulsed with the loss of 8,000 men. The daring Skobeleff strove in vain to launch his troops over Osman's walls. At length General Todleben undertook the siege, adopting the slow but safe method of starving out the defenders. Osman Pacha now showed his courage, as he had already shown his endurance. When hunger and disease began to reduce the strength of his men, he resolve on a final desperate effort. At the head of his brave garrison the "Lion of Plevna" sallied from the city, and fought with desperate courage to break through the circle of his foes. He was finally driven back into the city and compelled to surrender. [=The Total Defeat of the Turks=] Osman had won glory, and his fall was the fall of the Turkish cause. The Russians crossed the Balkan, capturing in the Schipka Pass a Turkish army of 30,000 men. Adrianople was taken, and the Turkish line of retreat cut off. The Russians marched to the Bosporus, and the Sultan was compelled to sue for peace to save his capital from falling into the hands of the Christians, as it had fallen into those of the Turks four centuries before. Russia had won the game for which she had made so long a struggle. The treaty of San Stefano practically decreed the dissolution of the Turkish Empire. But at this juncture the other nations of Europe took part. They were not content to see the balance of power destroyed by Russia becoming master of Constantinople, and England demanded that the treaty should be revised by the European powers. Russia protested, but Disraeli threatened war, and the czar gave way. [=The Congress of Berlin=]