Short answers, pulled from the story.
Sextus Pompey was a Roman commander who led a naval blockade against Rome after his father Julius Caesar's assassination. He used Sicily as a base to cut off grain shipments and destabilize the Triumvirate.
The conflict occurred between 42 BC and 36 BC following the death of Julius Caesar on the 15th of March 44 BC. Major naval battles concluded with Agrippa defeating Sextus near Mylae in August 36 BC.
Sextus Pompey captured cities including Tyndaris, Mylae, Messina, Syracuse, Sardinia, Corsica, and Sicily. His fleet operated from these locations to control sea lanes around the Italian Peninsula.
Marcus Agrippa constructed Portus Julius by cutting part of Via Ercolana to connect Lucrine Lake to the sea. This harbor allowed him to train 20,000 oarsmen and build larger ships equipped with harpax and corvus weapons.
Agrippa defeated Sextus near Mylae in August 36 BC using heavier units armed with harpax and corvus weapons. The engagement destroyed much of Sextus' fleet while Agrippa lost only three ships out of 300 total vessels.