Thus Russia and England had changed places in their attitude toward Bulgaria. Both had realized that they had made a mistake seven years previously; that Bulgaria herself would have a word to say as to whether she was to become a Russian province. Having failed to persuade Turkey to take military steps to bring Eastern Rumelia back under her rule, Russia now turned to Serbia. Greece and Serbia were also furious that Bulgaria should suddenly acquire territory without their having a share in it, thus making her the biggest nation of the Balkans. So Serbia and Russia intrigued together. The result was that, like the proverbial bolt out of a clear sky, Serbia hurled a declaration of war at Bulgaria and began marching her army across the frontier toward Sofia. The Bulgarian army was in Eastern Rumelia at the time, expecting trouble from the Turks. When the news came that the Serbians were attacking them from the rear, they began rushing up north. They packed themselves into the box cars on the railroad like dried fish, and they clung to the tops like insects. Meanwhile the people of Belgrade toasted their sovereign, King Milan, as "King of Serbia and Macedonia." Three days later the Serbian army was well on the road over the frontier toward the Bulgarian capital. Suddenly, at Slivnitza, a small town just over the frontier, the Bulgars burst down on them. At their head rushed a brigade of 3,000 Macedonian "brigands," natives of that territory that the Treaty of Berlin had cut off from Bulgaria. With the Bulgarian army was also a corps of 6,000 Mohammedan volunteers who rushed into the battle with as much enthusiasm as their Christian fellows. At that moment Bulgaria reaped the benefits of the tolerance she had shown the Mohammedan population during the seven years of her independence. They were now good Bulgarian citizens. The war with Serbia lasted just three days. At the end of that time the Serbians were flying, a panic-stricken mob, back across the frontier toward Belgrade, the Bulgars at their heels. At their head, in the midst of the flying bullets, rode Prince Alexander. The war was won in spite of the fact that all the Russian officers, acting on secret instruction from home, had resigned on the day before the battle. The Bulgarian army had already advanced to and occupied Pirot, and was preparing to continue on to Belgrade, when Count Khevenhueller, the Austrian Minister to Serbia, arrived at Bulgarian headquarters and informed Prince Alexander that if the Bulgarians continued their advance the Serbians would be joined by Austrian troops. The prince yielded to superior force, and in March, 1886, a treaty of peace was signed at Bucharest. Serbia did not cede a single yard of territory, nor did she pay one cent of indemnity. Not only Russia, but Austria, was beginning to fear Bulgaria; neither wanted a really formidable power in the Balkans. But at any rate the union with Eastern Rumelia was accomplished and remained a fact.