Pomorie) on Bulgaria's Black Sea coast. The Byzantine generals planned to outflank the Bulgarian right wing in order to detach Simeon's troops from the Balkan Passes. The Bulgarian ruler concentrated his most powerful forces in the two wings and left the centre relatively weak in order to surround the enemy when the centre would yield to the Byzantine attack. Simeon himself was in charge of large cavalry reserves hidden behind the hills which were intended to strike the decisive blow. The Byzantine attack was fierce and it was not long before the Bulgarians began slowly to retreat. The Byzantine cavalry charged the infantry in the centre killing many Bulgarians. The Bulgarian position became desperate as they could not manage to hold the heights to the south of the river and began a hasty retreat to the north. Elated, the Byzantines started a bitter chase and their battle formations soon began to break, especially as a rumour spread that the Byzantine commander, Leo Phocas, had been killed. At this point, Simeon, who had detected the disarray in the Byzantine formation, ordered his army to stand, and, at the head of his heavy cavalry corps, attacked the Byzantine left wing from behind the hills. With an irresistible onslaught the cavalry bore down at the confused enemy who immediately bent under their attack, panicked, and took to their heels. Some Byzantines tried to repulse the cavalry charge but they were also attacked by the infantry. Tsar Simeon personally took part in the fight, his white horse killed at the height of the battle. The Byzantines were completely routed. Leo Phocas was saved by fleeing to Mesembria (modern Nesebar) in Bulgaria, but in the thick of the battle Constantine Lips, John Grapson, and many other commanders (archontes) were cut down along with an enormous number of soldiers and officers. By the end of the day the Bulgarians overwhelmed the defenders of Mesembria and captured the town. Leo Phocas barely escaped by boarding a ship. The Byzantine historian Leo the Deacon says that 75 years after this military catastrophe the field at Anchialus was still covered with tens of thousands of Roman skeletons. The battle was among the bloodiest of medieval history and some historians refer to it as "the battle of the century". Aftermath The remainder of the Byzantine army fled all the way back to Constantinople, followed by the Bulgarians. Several days later