No surviving ancient historical text mentions the career or fate of Marcus Insteius after the Battle of Actium.

The definitive historical consensus is that the trail goes cold for Insteius immediately following the conflict in 31 BC. [1, 2]

The primary reasons for this lack of documentation include:

1. The Battle of Actium Was His Final Historical Record

Marcus Insteius is only known in narrative history as a loyal partisan of Mark Antony. In Plutarch's Life of Antony, he is recorded as commanding the center of Antony's fleet alongside Marcus Octavius. Because Antony's center line was thoroughly defeated and abandoned during the chaotic retreat sparked by Cleopatra's escape, it is highly probable that Insteius was either killed in action, captured, or executed by Octavian (the future Emperor Augustus). [1, 2, 3]

2. Ambiguous Archaeological Namesakes

While literary records completely vanish after 31 BC, there are distinct epigraphical traces of other figures named "Insteius" that historians have attempted to reconcile: [1, 2]

• The Corinthian Coins: Prior to Actium (around 42–33 BC), an M. Insteius Tectus served as a local magistrate (duovir) in Corinth, issuing bronze coins under Mark Antony’s eastern administration. Though some scholars have debated whether he managed to defect and survive the purges, there is no concrete proof of his activity extending after Octavian’s final victory. [1, 2, 3]
• The Military Descendants: Centuries later, names like Insteius Capito (a camp prefect under Nero) appear in the Tacitus Annals. Historians generally believe these later figures were simply descendants or individuals from the same family clan (Insteia gens), rather than the Actium commander himself. [1, 2, 3, 4]

If you are researching this family or a related historical event, let me know if you would like me to track down more details on Mark Antony's command structure or look into the epigraphical records of Corinth during that transition period!

L'AI può commettere errori, quindi verifica le risposte 

do we know his strategy for that central part?

Yes, historians understand the central strategy, but it was a reactive and defensive one dictated by Antony's overarching battle plan. Marcus Insteius did not have an independent offensive strategy; rather, his center was assigned a highly specific role designed to make Mark Antony’s grand gamble work. [1, 2]

The strategy for the center portion of the fleet can be broken down into three key elements:

1. Act as an Anchor and Avoid the Lure

Antony’s primary plan was for his powerful left and right wings (commanded by Sosius and Antony himself) to fan outward and envelope the flanks of Octavian’s fleet, which was commanded by Marcus Agrippa. [1, 2]

• The Center's Job: Insteius and Marcus Octavius were ordered to keep the center of the line completely stationary and tight.
• The Trap: Agrippa recognized this and deliberately backed his own ships up into open water, trying to lure Antony's fleet out into a looser formation. While the outer wings took the bait and advanced, Insteius’s center initially held the line to avoid creating gaps that Octavian's smaller, highly maneuverable ships could exploit. [1, 2, 3]

2. Guard the Screen for Cleopatra’s Breakout

The most critical—and controversial—strategic purpose of the center was to act as a physical shield. [1]

• Directly behind Insteius’s central squadron sat Cleopatra and her 60 Egyptian merchant warships, packed with the royal treasury.
• Insteius's center was deliberately kept dense to block Octavian's forces from seeing or reaching Cleopatra’s squadron. The plan from the beginning was likely a breakout attempt rather than a fight to the death. Insteius had to hold the line just long enough for the afternoon thermal winds to shift to the south, creating the perfect breeze for a retreat. [1, 2, 3, 4]

3. The Collapse: Absorbing the Fatal Blow

Because Insteius's center was instructed to hold back while the wings advanced, a massive tactical gap inevitably opened up in Antony’s crescent formation. [1]

• When the wind shifted, Cleopatra's squadron hoisted their sails and charged straight through the gaps in Insteius’s center, fleeing toward Egypt. [1]
• Once Antony abandoned his flagship to follow her, the morale of the center completely shattered. Insteius’s strategy shifted from a structured defense to a chaotic containment disaster. His heavy, towering ships were surrounded by Agrippa’s swifter vessels, which used missiles, fire, and boarding grappling hooks (the harpax) to systematically destroy the abandoned center line. [1, 2, 3]

Would you like to explore how Agrippa’s specific naval tactics broke through that central wall, or look closer at the debate among historians over whether Actium was always meant to be a breakout escape?