XI. Besides writing to Pyrrhus in this strain the kings themselves contrived to find work for Demetrius, who was still engaged in preparations for his campaign. Ptolemy sailed to Greece with a large force and induced many of the Greek cities to revolt from Demetrius, while Lysimachus, starting from Thrace, invaded and plundered Upper Macedonia. At the same time Pyrrhus marched upon the city of Berœa, truly conjecturing that Demetrius, in his haste to repel the invasion of Upper Macedonia, would leave the lower part of the country unprotected. That night he dreamed that he was called by Alexander the Great, and that he at once went to him, and found him reclining on a couch. The hero received him kindly, and promised him that he would aid him. When Pyrrhus mustered courage to ask, "How, O king, being yourself ill, can you assist me?" Alexander answered, "With my name," and mounting a Nisæan horse appeared to lead the way. This dream gave Pyrrhus great confidence: he quickly marched over the intervening country and took Berœa, where he fixed his headquarters, and sent out detachments to reduce other places. Demetrius, when he heard this news, and heard also the tumult of grief and indignation which it excited in his camp, feared to march any closer to Lysimachus, lest if his army came near to a king who was a Macedonian, and so distinguished a man, the troops might transfer their allegiance to him. He therefore resolved to retrace his steps, and attack Pyrrhus, as being a foreigner, and an enemy of the Macedonians. However, when he pitched his camp near Berœa, many came out from that city loudly praising Pyrrhus, as an invincible warrior and a great man, who had treated the vanquished with kindness and magnanimity. Some of these were emissaries of Pyrrhus himself, disguised as Macedonians, who said that now was the time for them to relieve themselves from the harsh tyranny of Demetrius by adopting Pyrrhus, a popular man and a true friend of the soldier, as their king. The greater part of Demetrius's troops was much excited by this means, and when the two armies met face to face, all eyes were turned in search of the hero. For a time they could not find him, for he had taken off his helmet; but when he had put it on again, and enabled them to recognise him by the lofty crest, and the goat's horns at the sides, the Macedonian soldiers quitted their ranks, and came running up to ask him, as their chief, for the pass-word. Others, seeing that his attendants wore garlands of oak-leaves, crowned themselves in like manner. Some already ventured to tell Demetrius that his best course would be to give up all as lost: and he, observing, that this advice seemed to be borne out by the temper of his army, withdrew in terror, disguised in a mean dress, and a broad-brimmed Macedonian hat. Pyrrhus, advancing without striking a blow, obtained possession of his enemy's camp, and was saluted king of the Macedonians.