Aristobulus of Cassandreia (Ἀριστόβουλος ὁ Κασσανδρεύς) was a Greek historian of the 4th century BCE. He participated in the campaigns of Alexander the Great, though his precise role—whether as an architect, engineer, or soldier—remains unclear [1]. A contemporary of Alexander, he began composing his history at an advanced age, reportedly after 84 [1][2]. His city of origin, Cassandreia, was a Macedonian city originally named Potidaea and later refounded by Cassander [3].

His only known work is the History of Alexander, a detailed account of Alexander's campaigns written late in his life. The text does not survive intact but is preserved in fragments and through extensive quotation by later historians like Arrian [1][2][4].

Aristobulus is a significant primary source for Alexander's reign. Alongside Ptolemy I Soter, he was one of Arrian's two main sources for the Anabasis of Alexander; Arrian praised him for his reliability and accuracy [1][2]. His work exhibits a rationalizing tendency, offering naturalistic explanations for events often considered miraculous [1][2]. Later historians like Strabo and Plutarch also used his history, which provides valuable participant perspectives on geography, events, and Alexander's character [1][2].

Sources 1. Stanford Encyclopedia of Philosophy: Aristobulus of Cassandreia (https://plato.stanford.edu/entries/alexander-the-great/supplement2.html) 2. Encyclopædia Britannica: Aristobulus of Cassandreia (https://www.britannica.com/biography/Aristobulus-of-Cassandreia) 3. Perseus Digital Library: Entry for "Cassandreia" (http://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.04.0064:entry=cassandreia-geo) 4. Oxford Research Encyclopedia of Classics: Search for "Aristobulus" (https://oxfordre.com/classics/)