Kynnane put her plans into motion even before the conflict between the Successors sharpened. [...] After the conclusion of the Lamian War and shortly after Kleopatra had set off for Sardeis, Kynnane assembled an army and headed off to Sardeis as well with her teenage daughter Adea. Antipater, flush from his victory over the Greeks in the Lamian War, had let his guard down and allowed Kleopatra to slip through his fingers and go to Asia Minor. So when Kynnane and Adea tried to do the same, he gathered troops to stop them from crossing the river Strymon near Amphipolis in eastern Macedonia, but Kynnane and her army forced their way across.
Kynnane‘s plan was to marry her daughter Adea to Philip Arrhidaios. No doubt she had learned of the army forcing the generals to appoint Arrhidaios as joint-king with Alexander IV and planned to exploit this. Adea was doubly Argead, through her mother who was daughter of Philip, and from her father Amyntas who had been the son of Philip's brother. In addition Kynnane had personally given her daughter a martial education, just like she had received from her own mother. These two in combination should in theory make her the perfect queen in the eyes of the Macedonian soldiery; a royal Argead through and through as well as trained in the ways of war. The fact that she was actually able to swiftly recruit at least enough troops to force her way out of Macedonia, whether this was an "army" or just a sizeable escort, says a lot of the Macedonians‘ loyalty to their royal family.
However, Kynnane's bold scheme threatened virtually everyone in the faction-riddled Macedonian power politics at this stage. It threatened Perdikkas, who would lose control over Philip Arrhidaios if either Adea or Kynnane, or both in tandem, started to pull the strings using mentally challenged Arrhidaios as a mouthpiece. It threatened Kleopatra and Olympias because a son by Adea and Arrhidaios would automatically move further up the line of succession, ahead of any child by Kleopatra. It also threatened Antipater and his control over Macedon and Greece since he had already made an enemy of Kynnane by trying to stop her, and only a year later Adea and Antipater would be at loggerheads. Kynnane had support from none of the generals, so she intended to do like Alexander and cut straight through this Gordian knot of political factions. Kynnane must have known the dangers of this course of action and despite outmanoeuvring Antipater and Kleopatra she paid for it with her life. As she and Adea and their troops reached Sardeis they were met with a substantial force from the royal army led by Perdikkas‘ brother Alketas. Alketas ordered her to turn back, acting on orders from his brother the regent, but when Kynnane refused Alketas had her killed in front of the two armies. The soldiers of both armies, horrified at the sight of Kynnane's death, mutinied and demanded Adea be allowed to marry Philip Arrhidaios as Kynnane had wanted. Perdikkas, suddenly finding himself at the wrong end of an irate and unruly Macedonian army again, relented and the marriage took place at Sardeis in 321.
Polyainos might be overly dramatic in his brief account of Kynnane‘s actions, possibly aimed at making her seem like an exotic warrior-princess rather than a proper Hellenistic woman. Yet there is no doubt about Kynnane being a clever politician and knew she and her daughter were outsiders in the dynastic struggle, yet managed to strong-arm the Successors sufficiently to place her daughter on the throne as queen. It did however cost Kynnane her life but it was a strategy of dynastic survival, and she must have been aware of the very real danger of her mission to Asia Minor. That is not to say she expected to be killed, she likely imaged she would remain in a role similar to what Olympias tried to do, be the queen's main advisor and see to it that everything went according to plan. She did not take into account Alketas' and Perdikkas' lack of touch with the Macedonian rank-and-file in the royal army. Perhaps more so than her sister Kleopatra, Kynnane had her ears to the ground and recognized the most effective route to power would be the direct one; military support and strength without the intermediary of a Perdikkas or a Leonnatos, and knew the Macedonian soldiers would remain loyal to the Argead family. It was a wholly untraditional choice of strategy for a woman in the Greco-Macedonian world, but it worked, and Adea, who became Eurydike on her marriage to Arrhidaios, learned from her mother's example and would use the same strategy over and over again in her brief but spectacular career as queen.
— Øystein Wiklund Lyngsnes, "The Women Who Would Be Kings": A study of the Argead royal women in the early Diadochoi Wars (323-316 BCE): The Rivalry of Adea-Eurydike and Olympias and the Death of the Argead dynasty (2018)