While his father Sparadocus is the first Odrysian monarch to have left proven coinage, Seuthes succeeded his uncle Sitalces on the throne in 424 BC.
[1] Although the contemporary Thucydides merely indicates that Sitalces died during the course of an unsuccessful campaign against the Triballi and was succeeded by his nephew Seuthes,[2] the circumstances, paired with a later accusation of Philip II of Macedon against the Athenians (that on the death of Sitalces, whom they had admitted to their citizenship, they immediately made an alliance with his murderer[3]), some scholars have seen Seuthes' accession as the result of a conspiracy.
[4] This does not necessarily follow,[5] and Seuthes is already described as Sitalces' highest official before his succession to the throne.
The prospect of the marriage and dowry are said to have induced Seuthes to counsel his uncle to withdraw his forces from Macedon.
Whether Seuthes' policy was due to loyalty, to prudent neutrality in the face of rapidly changing conditions and alliances, to preference for peace, or to incapacitation due to weakening of control over subject peoples is unclear.