Alexander the Great > Wars of the Diadochi
Wars of the Diadochi

Background

Alexanders Empire (336-323 BC) - Historical Atlas (1923)
Following the conclusion of the Indian Campaign the Macedonians under the leadership of Alexander III the Great returned back to the city of Babylon. However, while in Babylon plotting a campaign to take over Arabia the young Alexander suddenly and unexpectedly died in 323 BC he left no male heir and a massive empire. His empire was not culturally homogenous but instead composed of many different satrapies from the previous Achaemenid Empire that would all needed to be held together.
There was immediate disputes among his generals and friends known as the Diadochi as to who should succeed Alexander as king. While there appeared to be a peaceful resolution and transition after his death all was not well among Alexander's old companions. Within a few years there began a great conflict called the Wars of the Diadochi that lasted between 322 BC and 281 BC between the various factions of Alexander's old empire known as the Hellenistic Kingdoms. In addition to this there many other wars that broke out as a result of the power vacuum created by the death of Alexander such as the Lamian War and the Syrian Wars.
The Wars of the Diadochi would result in the establishment of three-four major kingdoms throughout the known world. In the end Ptolemy I Soter would establish the Ptolemaic Kingdom of Egypt along with territories in Asia Minor and Syria. Seleucus I Nicator ruled over the massive Asian territories under the Seleucid Empire. Macedon and the rest of Greece would be ruled over by Antigonus I Monophthalmus.

Kingdoms of the Diadochi Map - Historical Atlas (1923)
The Diadochi
See The Diadochi
It is important to understand who each of the diadochi was that was vying for control over Alexanders empire. Each of these characters played an important role in the fragmentation of the massive empire.
Partition of Babylon
Lamian War
See Lamian War
First War of the Diadochi
Second War of the Diadochi
See Second War of the Diadochi
Third War of the Diadochi
Babylonian War
See Babylonian War
The Babylonian War (311–309 BC) occurred between Antigonus and Seleucus I over control in Mesopotamia. Even despite entering the city of Babylon in 310 BC, Antigonus was defeated. During the Babylonian War Cassander had the young Alexander IV and his mother Roxanne executed which effectively ended the Argead Dynasty which ruled Macedon for centuries including both Philip II and Alexander the Great.
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Not everyone knew of the execution of the young king at first and many of the former generals all saw him as the legitimate heir to the empire. This conflict ended any possibility of the reunification of Alexander's empire. It also marked the real establishment of the new Seleucid Empire that gave Seleucus I Nicator control over all the eastern portion of Alexander's empire from Mesopotamia to India.
By losing the war, Antigonus was forced to relinquish the territories of Elam, Media and Babylonia. At this point on Seleucus more or less occupies most of the territory that was previously controlled by the Achaemenid Empire. The next series of wars would fully cement the fact that reunification of the empire was no longer possible at this point.
Fourth War of the Diadochi
See Fourth War of the Diadochi
Syrian Wars
See Syrian Wars