Short answers, pulled from the story.
The Roman fleet first appeared in the historical record around 311 BC when two officials known as duumviri navales were appointed to maintain a small group of ships. Livy records that this initial force consisted of just twenty vessels, likely triremes, with each official commanding ten ships.
Roman crews developed an innovative weapon called the corvus boarding bridge to transform sea combat into familiar land warfare where legionaries held the advantage. This long plank featured a spike designed to hook onto enemy ships, allowing marines to board vessels and fight on deck rather than relying on ramming tactics.
Octavian commanded four hundred ships against Mark Antony and Cleopatra's five hundred vessels at the great naval Battle of Actium in 31 BC. This final engagement established Octavian as sole ruler over Rome and the Mediterranean world before he became Emperor Augustus.
Emperor Claudius first granted legal privileges to naval crewmen in the early Empire enabling them to receive Roman citizenship after completing service periods initially set at twenty-six years and later expanded to twenty-eight. Upon honorable discharge called honesta missio sailors received substantial cash payments alongside their new citizenship status.
Augustus formalized the navy structure by establishing permanent bases at Misenum and Ravenna creating two praetorian fleets directly available to the emperor. The Classis Misenensis operated from Portus Julius with detachments serving secondary bases like Ostia Puteoli and Centumcellae while the Classis Ravennas maintained operations from its namesake harbor.