When it grew certain that war would ensue, the Emperor Nicholas reinforced his army in the Principalities, and raised it to the strength of about 150,000 men, including an immense force of cavalry, and no fewer than 520 guns. Against this mass the Sultan could barely array a nominal force of 120,000 men, and a number of guns far inferior to that of his foe. The bulk of the Russians were in Wallachia, posted in detachments from Kalafat to Galatz. Their plan of operations was to concentrate a mass of troops opposite Silistria, to hold in check the Turks at Kalafat, on one flank, while on the other they invaded the Dobrudscha. It was then intended that the main body should cross the Danube at Kalarasch, and joining the troops coming up the river upon Silistria, invest and capture that fortress. This done, they hoped to capture or mask Varna, and forcing Shumla, debouch through the passes of the rugged Balkans upon the plains of Roumelia. Marshal Prince Paskiewitch had been appointed to command the army, and such is assumed to have been his plan of operations. But the plan was essentially vicious. They could not fail to lose men in the pestiferous Dobrudscha. So long as the Turks held Kalafat the Russians were never secure on that flank. Then, assuming that they kept the Kalafat army at bay, and even captured Silistria, it was in the highest degree improbable that they could force Shumla, and impossible that they could take Varna, so long as the allied fleets held the Black Sea. Nor were these the only dangers incurred by the Czar. The plains of Wallachia lie between the ridges of the Carpathians and the Danube. On their northern slopes Austria was collecting a formidable army. Austria, though not resolved to fight, was growing more menacing in her language and in her attitude. It was true that she trammelled herself by a treaty with Prussia, laying down the march of the Russians on the Balkans as a _casus belli_. But Russia had no security that circumstances might not occur to produce a change in Austrian councils, or that the very success of her preliminary movements might not bring Austria to act. And if she acted, she would move across the Russian line of communications, and the mere threat to do that would almost ruin the Russian plan.