Mithridates VI the Great

Mithridates the Great or Mithradates VI Eupator (135–55 BCE) was ruler of the Kingdom of Pontos, located first in northern Anatolia, then in all of Asia Minor, the Hellenic world and later southern Italy, from 120 to 55 BCE. He was an effective, ambitious and ruthless ruler who sought to dominate Asia Minor, the Black Sea region, and Europe waging several wars (the Mithridatic Wars), effectively claiming victory over all his enemies. He has been called the greatest ruler of the Kingdom of Pontos. It was him to found the prosperous city of Mithripolis on the foundation of Byzantion. Due to his affinity for poison, he has also been called The Poison King.

History
From Pontus#Under Mithridates VI the Great:

Mithridates VI Eupator, 'the Good Father', was far more ambitious than his predecessors. Mithridates began his expansion by inheriting Lesser Armenia from King Antipater (c.115–106 BCE) and by conquering the Kingdom of Colchis. Colchis was an important region in Black Sea trade – rich with gold, wax, hemp, and honey. The cities of the Tauric Chersonesus now appealed for his aid against the Scythians in the north. Mithridates sent 6,000 men under General Diophantus. After various campaigns in the north of the Crimea, he controlled all of the Chersonesus.

Mithridates VI the Great and Nicomedes III of Bithynia had become allies and both invaded Paphlagonia in 108 BCE and divided it amongst themselves. Mithridates VI also took a part of Galatia that had previously been part of his father's kingdom and intervened in Cappadocia, where his sister Laodice was queen. In 116 BCE the king of Cappadocia, Ariarathes VI, was murdered by the Cappadocian noble Gordius at the behest of Mithridates, and Laodice ruled as regent over the sons of Ariarathes until 102 BCE. After Nicomedes III of Bithynia married Laodice, he tried to intervene in the region by sending troops; Mithridates swiftly invaded, placing his nephew Ariarathes VII of Cappadocia on the throne of Cappadocia. War soon broke out between the two, and Mithridates invaded with a large Pontic army, but Ariarathes VII was murdered in 101 BCE before any battle was fought. Mithridates then installed his eight-year-old son, Ariarathes IX of Cappadocia, as king, with Gordius as regent. In 97 BCE Cappadocia rebelled against Mithridates VI and called for Nicomedes III brother, Ariarathes VIII of Cappadocia, who was in Pergamon for his education, to return to Cappadocia to become king. Mithridates invaded Cappadocia and drove him out. Ariarathes VIII died in 96 BCE. With his death, his dynasty died out. Nicomedes III now feared that Mithridates would invade Bithynia, which he would then do in the same year.

In 95 BCE, Mithridates VI invaded the Kingdom of Galatia, to ensure his position in Anatolia. Galatia then became a client state of Pontos. Mithridates invaded the Kingdom of Pergamon and all other remaining Anatolian kingdoms by 94 BCE. He was very popular amongst citizens, as he promised to not collect taxes for five years.

In 88 BCE, Mithridates the Great launched a massive invasion into the Macedonian Empire. The war started, when the Pontic general Archelaus crossed the Bosporus, while general Dorylaeus crossed the Hellespont. Both armies met the Macedonian king at the battle of Philippopolis (88 BCE). The Macedonian king was defeated. Losing 30,000 soldiers, he retreated to Pella, while his general Ariston arrived with 30,000 fresh troops for reinforcement. Mithridates was not willing to waste any time and ordered his general Neoptolemus to invade Athens by sea. Even though Macedonia had a naval superiority, most of its fleet was located near Thessalonica, to avoid being outflanked through the sea. Neoptolemus landed near Corinth and quickly captured the Peloponnese Peninsula. Ariston swiftly moved to Attica and attacked Neoptolemus' army, which besieged Athens. After the unsuccessful siege, in which Neoptolemus lost 15,000 men, the now outnumbered general retreated to the Peloponnese, though still being able to hold his position. However, because of Ariston's shift to the south, the northern army under the Macedonian king, was now outnumbered almost 2 to 1. Archelaus and Dorylaeus had taken this opportunity and attacked the Macedonian king in the Battle of Pella (87 BCE). The king was defeated, and after losing 30,000 men, he retreated to Thessalonica, where most of the Macedonian navy was located. Archelaus thus laid siege on Thessalonica and the king was now outnumbered 3 to 1.

Ariston was now ordered to move 30,000 of his 50,000 men to protect Thessalonica. Neoptolemus took this opportunity and defeated Ariston, killing 10,000 of his men near Athens. Ariston now retreated to the famous mountain pass of Thermopylae, where the outnumbered Spartans once engaged the Persians, while Neoptolemus captured Athens. However, Neoptolemus avoided the mountain pass and slowly advanced to the north, while Ariston had other choice but to retreat to Larissa. The general met Neoptolemus at the Battle of Larissa (87 BCE) and killed Ariston including most of his army. The king now had no other choice but to evacuate his entire remaining army and fleet to Italy. Even though the king was able to reinforce his army with another 30,000 men, his Italic holdings had become unstable and revolted. In early 86 BCE, Archelaus and most of the Pontic army landed in Italy. Eventually, the king was captured and executed, after the Battle of Taras (86 BCE). Macedonia was now completely under Pontic control.

During the invasion of Thrace, Archelaus sent Mithridates a letter about how profitable the location of Byzantion was, which connected the Aegean Sea with the Black Sea. Mithridates VI expanded the city and renamed it "Mithripolis", later serving as the largest city, but not the capital, of the Pontic Empire, though often referred to as the second capital of Pontos. Mithripolis thus became, after time, one of the most important cities in all of Europe and the Middle East.

Mithridates the Great established numerous vassal states, most dedicated to be ruled by his sons, which are listed as follows:


 * 1) Mithridates of Colchis: ruled the vassal kingdom of Colchis.
 * 2) Machares: ruled the vassal kingdom of Achaea.
 * 3) Arcathias: ruled the vassal kingdom of Epirus.
 * 4) Pharnaces II: ruled the Bosporan kingdom; successor of the Pontic Empire after Mithridates' death.
 * 5) Xiphares: ruled the vassal kingdom of Athens.
 * 6) Mithridates I of the Bosporus: ruled the vassal kingdom of Crete.
 * 7) Ariarathes IX of Cappadocia: ruled the vassal kingdom of Cappadocia; however, was actually ruled by general Gordius until he was an adult.

Mithridates' Brother, Mithridates Chrestus, was a first a co-ruler of the Pontic Empire and later vassal king of Macedonia.

Due to his great strategies in the Macedonian War (88-86 BCE), Archelaus was granted the vassal kingdom of Thessaly.

Mithridates VI the Great died in 55 BCE. His empire, however, experienced a short period of instability, continued under his son and successor, Pharnaces II.

Source
https://en.wikipedia.org/wiki/Mithridates_VI_Eupator

Image credits
By Sting, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=408281