Battle of Ipsus: The Greatest Clash of Alexander’s Successors

The death of Alexander the Great in 323 BCE resulted in a scramble for control over his vast empire. For nearly twenty years the Diadochi, or Successors, fought amongst themselves first for the entire empire and then for its parts. By 308 BCE, Alexander’s empire had been divided between the five most powerful and effective of the Diadochi. This set the stage for the so-called Fourth War of the Diadochi (308-301 BCE), which eventually culminated in the Battle of Ipsus (301 BCE). It was this battle that forever ended the possibility of reuniting Alexander’s empire, and which determined the political and military fault lines for the rest of the Hellenistic Period. It was a true Hellenistic “clash of titans.”

In the years following the death of Alexander the Great in 323 BCE his surviving family members and generals vied for control of the empire. Slowly the Diadochi, or successors, eliminated each other and consolidated their positions. After the end of the Second War of the Diadochi 319-315 BCE, the empire was divided between four major Successors. The most powerful of these was Antigonus Monophthalmus who ruled over Anatolia, Syria, Cyprus, the Levant, Babylonia, and all the territories of further east. He was opposed by Cassander, who ruled Macedonia and much of Greece, Lysimachus, who controlled Thrace, Ptolemy, who ruled in Egypt, and Seleucus the former satrap of Babylonia who had been driven from his post by Antigonus.

This coalition against Antigonus proved to be highly effective. Antigonus lost territory to the other Diadochi so that he was reduced to ruling over Anatolia, Syria, Cyprus and the Levant. Seleucus increased his territories the most, first regaining Babylonia and then taking control of all the satrapies to the east. This brought Seleucus into contact and possibly into brief conflict with the growing Mauryan Empire and its founder Chandragupta Maurya. Having failed to prevent Seleucus from regaining control of Babylonia, Antigonus turned his attention to the Aegean where Ptolemy had been expanding his power. This led to a general resumption of hostilities in 308 BCE known as the Fourth War of the Diadochi (308-301 BCE), which would ultimately culminate in the Battle of Ipus.

Long March to Ipsus

With the general resumption of hostilities in 308 BCE, the aging Antigonus sent his son Demetrius into Greece. In 307 BCE Demetrius succeeded in expelling Cassander’s forces from Athens and proclaimed the city free again. This move won him the support of most of Greece, which was brought over to the Antigonids. Demetrius then turned his attention to Cyprus, where he defeated a large Ptolemaic naval force. These victories led Antigonus and Demetrius to proclaim themselves kings of Macedon, a move that was soon followed by Ptolemy, Seleucus, Lysimachus, and eventually Cassander. This was a significant development, as previously, the Diadochi had claimed to have been acting on behalf of Alexander’s family or in honor of his memory. Antigonid operations against Ptolemy and his allies in 306 and 305 BCE were largely unsuccessful but paved the way for operations against Cassander.

By 302 BCE, the war was going so poorly for Cassander that he transferred half of his forces to Lysimachus for a joint invasion of Anatolia while he attempted to pin down Demetrius in Northern Greece. By this point, Seleucus had ended his largely unsuccessful conflict with Chandragupta Maurya in the East and was marching his army back to Anatolia. Lysimachus was unwilling to face Antigonus in open battle before the arrival of Seleucus and focused on keeping Antigonus occupied. However, when word finally reached Antigonus of Seleucus’s approach, he ordered Demetrius’s return with his forces from Greece and regrouped their armies. Both sides now assembled their armies and prepared for what would be the greatest battle of the age.

As befitted such a titanic clash, the Antigonids and their enemies both assembled large armies before the battle of Ipsus. Modern estimates of the forces involved are drawn from the accounts of the Greek historian Diodorus Siculus (c.90-30 BCE) and the philosopher Plutarch (c.46-119 CE). Based on their accounts, it is believed that the Antigonids were able to field around 70,000 infantry, of which 40,000 were pike-wielding phalangites while the other 30,00 were light troops of various kinds. They also had roughly 10,000 cavalry and 75 war elephants. The majority of this force had been gathered by Antigonus as he marched through Syria. Demetrius had an estimated 56,000 troops in Greece, but it is unclear how many crossed over to Anatolia with him, as many would have been from allied Greek cities.

There are some questions about exactly how many troops each of the allies brought to the field during the battle of Ipsus. The total number of allied infantry is believed to have numbered 64,000 of which 20,000 were supplied by Seleucus. The remaining 44,000 were contributed by Cassander and Lysimachus, with the majority belonging to Lysimachus. Of these troops, 30-40,000 were phalangites, with the rest once again being light troops. Modern experts estimate the allied cavalry at 15,000, with around 12,000 having been brought by Seleucus. Additionally, Seleucus also brought 120 scythed chariots and 400 war elephants which he had received from Chandragupta Maurya and which would play a pivotal role in the battle of Ipsus.

By this point, both the Antigonids and their allies had settled on battle as the best method for achieving their strategic goals. The Antigonids would have preferred to defeat their opponents in a piecemeal fashion as they were much more powerful than any one of the other Diadochi. However, the opportunity to deal with all of them at once was too good to pass up. After all, Hellenistic generals and monarchs often emulated Alexander by leading from the front where the danger was. For the allies, battle represented their best chance to defeat Antigonus and Demetrius rather than allowing themselves to be overcome individually. A victory here could end the Antigonid threat forever.

Both armies relied on the same tactics; tactics which had proven so effective for Alexander. They relied on level ground where they could employ their massive phalanxes to pin and hold the opposing line. A strong cavalry attack, supported by light infantry was then launched on the right to envelop and shatter the enemy flank. In symmetrical warfare such as this, it was not uncommon for the opposing side to employ novel weapons like scythed chariots and war elephants to try and gain some advantage. At the battle of Ipsus, the Antigonids had the advantage in the number and quality of their infantry and cavalry while the allies had the advantage in war elephants. As such, they needed to make the best tactical use of the elements to win.

The Diadochi Deploy

The exact location of the battle of Ipsus is unknown other than that it was fought near the town of Ipsus in Phrygia (modern Çayırbağ in Turkey). Both sides appear to have deployed their troops in what was the standard Macedonian/Hellenistic formation of the period. The center of the battle line was a phalanx of pike-wielding heavy infantry. The light infantry were deployed as skirmishers in front of the phalanx and to either side to protect the phalanx’s vulnerable flanks. Cavalry was placed on either flank, with the most numerous and best units being deployed on the right, where they would form the main striking force. Usually, war elephants were with the light infantry, as horses were frightened of them, where they were used to try and break through the enemy’s main battle line. Scythed chariots were usually also deployed in this manner.

At Ipsus, Antigonus and his bodyguard were positioned at the center of the Antigonid battle line behind the phalanx, where he could more effectively issue commands. Demetrius commanded the Antigonid cavalry on the right wing, which was the main striking force. The position of the allied commanders is less certain. Seleucus appears to have held the overall command as he had the largest contingent of troops but it is unclear where on the battleline he was positioned. His son, Antiochus, commanded the allied cavalry on the left wing opposite Demetrius. It is believed that Lysimachus may have commanded the allied phalanx. Cassander was not present at the battle of Ipsus, so his troops were led by a general named Pleistarchus whose position is unknown. The key question regarding the allied deployment is where Seleucus placed his elephants. Roughly 100 appear to have been deployed with the light infantry. It has been suggested that the remaining 300 were kept in a tactical reserve directly commanded by Seleucus, but this would have been highly unusual for the period.

Fighting began with the armies advancing on their opposite numbers. First contact was made by the elephants and light infantry of the opposing armies. The ancient sources report that the battle of Ipsus began with a clash of war elephants. It was an equal contest which suggests that Seleucus had not deployed the majority of his elephants to the frontlines. The light infantry would have also engaged at this time, but it does not appear that either side was able to gain a clear advantage over the other. While this was going on, the phalanxes would have been advancing toward each other, but because these were dense formations, they moved very slowly.

The main action at this time was being fought on the wings by the cavalry. According to the Macedonian/Hellenistic tactical doctrine of the period, the main attack was delivered by the cavalry of the right wing. The weaker cavalry formation on the left wing was to buy time through skirmishing, to hold the enemy in place, and protect the flank of the phalanx. Demetrius launched a ferocious attack which he skillfully maneuvered around the allied light infantry and elephants. After a sharp fight, he utterly routed the cavalry under Antiochus and pursued them from the battlefield. However, he appears to have pursued too far and became isolated from the rest of the Antigonid forces.

Elephants at Ipsus

With the Antigonid and allied phalanxes now engaged in a brutal and chaotic fight, the time would have been ripe for Demetrius to have delivered a knockout blow. The expectation would have been for him to attack the rear of the allied phalanx or to return to his original position and protect the flank of the Antigonid phalanx. However, he was now too far away to do so and even when he realized his error, he soon found his way blocked. While Demetrius was off pursuing the allied cavalry, Seleucus maneuvered the 300 war elephants of his reserve to block the Antigonid cavalry’s return. Horses are terrified by the sight, smell, and noise of elephants and will refuse to approach without special training. As such, Seleucus’ maneuver effectively removed Demetrius and the Antigonid cavalry from the battle.

Seleucus then sent the rest of his cavalry, which included horse archers, from the allied right to threaten the exposed right flank of the Antigonid phalanx. Though the allied cavalry feigned several charges they never actually charged instead gradually wearing down the morale and stamina of the Antigonid troops. Antigonus attempted to rally his troops from the center of his line even as some defected to the allies. Hemmed in on all sides, Antigonus was eventually killed by several javelins, still believing that Demetrius would return at any moment and rescue him.

In the aftermath of the battle, the allied forces do not appear to have conducted a particularly vigorous pursuit. The hard fighting had likely exhausted their troops and they were more interested in dividing Antigonus’ territory between them. Demetrius, however, managed to recover 5,000 infantry and 4,000 cavalry from the wreckage of the Antigonid army. With these forces, he fled first to Ephesos in western Anatolia and then to Greece. There he found that his erstwhile allies were abandoning him in favor of the other Diadochi. Sailing to Thrace, he would continue to wage war against the other Diadochi for many years and even claim the Macedonian throne for himself and his descendants until the Roman conquest.

The battle of Ipsus was perhaps the greatest battle of the age. Although the last, best chance to reunite the empire of Alexander had already passed, the battle of Ipsus served to confirm this. Antigonus’ territory was seized by Seleucus, Lysimachus, and the ever-opportunistic Ptolemy. As such, the battle of Ipsus, more than anything else, finalized the breakup of Alexander’s empire. The former allies soon turned on each other, sparking a series of wars and conflicts that would shape the history of the Hellenistic period until their dynasties were eventually overthrown by the rising power of the Romans and Parthians.