The first Aegaeon passenger ship was serving the Greek seas after 1915. In fact, it is really the "second" ship with this name as there was another (wooden) vessel in the 1850s...
Here is an October 19, 1919 schedule when the ship belonged to the Mikrasiatiki Shipping of P. Makris, otherwise known as the Archipelagos Shipping Co. Here Aegaeon goes from Piraeus to Chios, Smyrna, Mytilene, then north to Kavala, west to Thessaloniki and then south to Chalkida and Piraeus!!!
19191019 Aeg Ag Spyridon.jpg
Two months later (December 2 and 18, 1919), Aegaeon is doing almost the same schedule
19191202 Archipelagos.jpg19191218 Alexandros.jpg
Here is the old ship!
Aegaeon old.jpg