Epibatoi

Notwithstanding the Spartan defeat at Aegosopotami almost a hundred years ago, the Athenian link to the sea remains still as strong as evidenced by the Epibatoi, or marines. These are units trained to function as marine infantry do - to fight on both land and sea, and to function as the vanguard of any amphibious operations. While Epibatoi are the Athenian equivalent of the Thureophoroi, there is a fundamental difference — they are capable of entrenching themselves on land if left to their own devices alone, and any transports carrying them move faster on the oceans.
Thus, Epibatoi are the perfect unit for proclaiming Athenian supremacy wherever you go. There are but a few caveats though. While they function as Thureophoroi, they are very much just as vulnerable as normal Thureophoroi are to the usual counters — engagements with heavy cavalry and heavy infantry. Epibatoi are extremely vulnerable if attacked with ranged bow cavalry, or if they are swarmed by superior numbers. So the trick to using Epibatoi is to recognise that while they are useful as a defending force, they cannot hold out on their own — a force of Epibatoi needs its own complement of cavalry and infantry escorts to keep it safe on the field.