
Battle of Hyelion and Leimocheir

The Battle of Hyelion and Leimocheir saw the almost complete destruction by the Byzantines of a large Seljuq Turk army. The Seljuq army had been raiding Byzantine territory in the Maeander Valley in Anatolia, and had sacked a number of cities. The Byzantine force ambushed the Turks at a river crossing.
Background.
Following Emperor Manuel Komnenos's defeat at the Battle of Myriokephalon (1176) the Byzantines failed to implement all the conditions, particularly the destruction of border fortresses, demanded by the Seljuq sultan Kilij Arslan II as a prerequisite for a cessation of hostilities. A substantial Seljuq cavalry army, including Turcoman nomad auxiliaries, was dispatched into Byzantine territory, in the Meander Valley in western Anatolia, on a retaliatory raid. A Byzantine army under the general John Komnenos Vatatzes, the emperor's nephew, set out from Constantinople with instructions to intercept the Seljuq raiders. Vatatzes was given two other generals as his subordinates, Constantine Doukas and Michael Aspietes, and was able to pick up reinforcements as his army moved through Byzantine territory.
Battle.
The date of the battle is unknown, it has generally been ascribed to the year 1177 on the basis of its position within the narrative of Niketas Choniates.
The Turks, who had orders to ravage the Meander Valley as far as the sea-shore, sacked the Byzantine settlements of Tralles, Antioch, Louma and Pantacheir. As a result of these successes, they were loaded with plunder, including, rather poetically, water from the sea, an oar and shore sand. These burdens would have drastically slowed their progress and lessened their tactical mobility. The Seljuq army was returning towards Turkish territory when it approached a "choke point" in its journey where the great eastern highway crossed the Meander River by way of a bridge (probably ruined or semi-derelict), near the villages, or forts, of Hyelion and Leimocheir. The Byzantines had concealed themselves and were divided into two corps, separated by the river. They caught the Seljuq army in an ambush when it had partially crossed over the river, destroying it as a fighting force. 
The Byzantine light troops played a prominent role in the battle; posted on high ground they are described as raining missiles down onto the near helpless Seljuqs. Many of the Seljuq soldiers tumbled into the river and were drowned. The Seljuq commander, known as "Atapakos" in Greek sources—evidently a bearer of the title of "Atabeg"—tried to help his forces cross the river by rallying the most heavily armed of his cavalry and attacking the Byzantines. This attack having failed, he tried to save himself by swimming across the river with his horse. When he reached the opposite shore, however, he was killed by an Alan soldier of the Byzantine force. Following the death of their commander the Seljuq troops fled in disorder, with a great number of them being drowned in the river; Choniates stating that only a few out of many thousands were able to save themselves. On the Byzantine side, the general Michael Aspietes fell; he was drowned in the Meander when thrown by his wounded horse.
Aftermath.
The battle was a significant Byzantine victory and it underlined how limited the immediate effects of the Byzantine defeat at Myriokephalon were on the empire's hold over its Anatolian possessions. The Byzantine victory was followed up by punitive expeditions against the Turcoman nomads settled around the upper Meander Valley.
The Byzantine strategy at this battle, ambushing a raiding army on its return journey when it would be slowed by plunder and captives, is exactly what is prescribed in much earlier Byzantine military treatises, such as the "Tactica" of Leo VI (886–912). This points to a retention by Byzantine commanders of knowledge of the successful military strategies of the past.
The emperor Manuel died in 1180; his son and successor Alexios II Komnenos was a minor, and the empire was governed by a divided regency. Without the strong presence of Manuel, the military advantage in Anatolia reverted to the Seljuqs. Sultan Kilij Arslan invaded the empire in 1182, when Byzantium was distracted by the coup d'état of Alexios's cousin Andronikos Komnenos, and following the Siege of Cotyaeum captured the towns of Sozopolis and Cotyaeum.