families from different cities formed a military alliance against Alexander II of Pherae. Once a united state, Thessaly fell into political instability following these developments. With a lack of leadership among the Thessalians, noble families took control in the 5th century BCE in an attempt to put an end to central authority. However, the internal conflict divided Thessaly into two sides: the western inland area of Thessalian League and the eastern coastal towns of Pherae controlled by the tyrants. One historian spoke of this period as follows, “Thessaly remained politically fragmented and hence unstable, and the chaos of civil war in the region attracted the interest of a series of outsiders: Boeotia, Athens, and eventually Philip II of Macedonia.” In the year 364 BCE, the new joint Thessalo-Boeotian army, led by the Theban general Pelopidas, marched to Alexander II of Pherae to intervene in the civil war. When the military result was not finalized, Pelopidas was summoned to enter the protracted struggle between Alexander II and Ptolemy Aloros in Macedonia- the Theban general, however, urged rearrangement of the Thessalian League at that time. The most important parts of the rearrangement were the replacement of the tagos by an archon, and the reorganization of the Thessalian army according to the four tetrads of Aleuas. Pelopidas’ death during the battle assured continuous regional civil war. In the late summer of 358 BCE, Alexander II of Pherae's death opened a path for Philip’s diplomatic conquest of Thessaly at the request of Cineas of Larissa. The civil war in Thessaly lasted for six years until Philip’s intervention put an end to it. War The League and Philip of Macedon In 355 BCE, Thebes convinced several members of the Amphictyonic League to declare war on Phocis, a fellow member of the League. Thessaly voted with Thebes, but when the Phocian general Philomelus defeated 6,000 troops fielded by the Thessalians, Thessaly divided into opposing regions. The tyrants of Pherae allied with Athens to support Phocis while the Thessalian League remained opposed to Phocis and sought the aid of Philip of Macedon. Philip was attracted by the military potential of the Thessalian League. Thessaly was famous for its horse-breeding as well as the skill and effectiveness of its cavalry, considered equal to Philip's own Macedonian Companions. When Philip answered the call for help and captured the port of Pherae, he became fully engaged on the Theban side