Sickles on the Masts: Decimus Brutus and the Naval Battle Against the Veneti, 56 BC

In 56 BC a Roman fleet under Decimus Brutus destroyed the Veneti navy in the Gulf of Morbihan using hooked poles to cut their rigging.

13 September 2026 · Part of Roman Empire & Republic — a guide to 23 articles →

In the summer of 56 BC, a Roman fleet built that same year on the Loire met the war navy of the Veneti in the open water of the Gulf of Morbihan, and won not by ramming or archery but by cutting rope. Roman crews fitted long poles with sharpened hooks, normally used against siege walls, and used them to sever the halyards holding the Veneti's leather sails to their masts. It was an improvised answer to a real tactical problem: the Veneti had built their ships for the Atlantic, and those ships were, by Caesar's own account, better suited to the fight than anything Rome could put on the water that year (Caesar, The Conquest of Gaul, Book III.7-16). The engagement is recorded in the campaign table of our record of Caesar's operations in Gaul and Britannia as the naval campaign against the Veneti, commanded not by Caesar in person but by his young legate, Decimus Brutus.

A Revolt Over Grain and Hostages

The trouble began the previous winter. In 57 BC the Veneti and other Armorican tribes of Brittany had submitted to Publius Crassus, son of the triumvir Marcus Crassus, handing over hostages as a guarantee of loyalty (BG II.34). Over the winter of 57-56 BC, Crassus's legion, quartered among the Andes near the Atlantic coast, ran short of grain, and he sent officers, including two named by Caesar as Quintus Velanius and Titus Silius, to requisition supplies from the coastal tribes (BG III.7-8). The Veneti seized them, and offered to trade the captured officers for the return of their own hostages. Several neighboring tribes — the Osismi, Lexovii, Namnetes, Ambiliati and others — joined the seizure and prepared for war rather than risk being singled out for punishment alone (BG III.9).

Caesar's own explanation is that the Veneti feared losing their hostages permanently and calculated, correctly for a season, that Rome's legions were poorly equipped for their terrain: tidal inlets, marsh and fortified promontories reachable only at low tide, ill-suited to infantry sieges (BG III.9, 12). Some modern historians note that Caesar had also just reconnoitered an expedition to Britain, and wonder whether the Veneti, who controlled the cross-Channel trade routes along this coast, had further reasons to resist a Roman fleet in their waters — a question the text itself does not answer.

Ships Built for the Ocean, Not the Mediterranean

Caesar's account gives an unusually detailed technical description of Veneti shipbuilding, and it is worth taking at face value even where his political framing should not be: the ships were built entirely of oak, with flat bottoms designed to sit safely on shoals and tidal mudflats, and bows and sterns raised high to survive Atlantic swells and storms that a Mediterranean galley could not have weathered (BG III.13). Their cross-beams were a foot wide and fastened with iron nails as thick as a thumb, their anchor cables were iron chains rather than rope, and their sails were made of raw or tanned hides rather than woven cloth or hemp — a design Caesar attributes either to a scarcity of flax or, more plausibly, to leather's greater resilience against Atlantic gales.

None of this made the Veneti ships fast. What it gave them was strength and height: they rode higher out of the water than the Roman vessels, built hastily on the Loire that same spring and crewed largely with rowers drawn from the Roman province rather than veterans of Mediterranean naval warfare. Roman ships could not easily ram the heavier oak hulls, and missiles thrown upward at much higher decks did little damage. The Veneti fleet — Caesar puts the number in the low 200s of ships, gathered from across the Armorican coast and its allies — mustered at the mouth of the gulf to meet the Romans as they arrived (BG III.14).

The Battle in the Gulf of Morbihan

Caesar states he watched the engagement from high ground on the shore with the bulk of his land army, unable to intervene directly (BG III.14). The Roman advantage lay only in oars and maneuverability, since a rowed vessel could turn inside a sailing ship becalmed or fighting the wind. Roman crews closed with individual Veneti ships one or two at a time rather than attempting a general melee, and it was here that Brutus's crews used the hooked poles — described in the sources as similar to the iron hooks Roman soldiers used against fortification walls — to grab and tear the ropes securing the yard to the mast (BG III.14). Once a Veneti ship's rigging was cut, its sail collapsed and the ship lost all way, since the Veneti had built no provision for rowing their oceangoing vessels under oar power alone (BG III.13-14).

Two or three Roman ships would then surround each disabled vessel and board it, overwhelming the crew in close combat where Roman legionaries training as marines had the advantage. As more Veneti ships were disabled, others tried to flee under sail toward open water. At that point, Caesar records, the wind dropped to a dead calm, leaving the surviving Veneti ships stranded and unable to maneuver at all (BG III.15). Roman ships rowed down the survivors one by one through the rest of the afternoon; by evening, according to Caesar, only a handful of Veneti ships reached shore out of a fleet that had numbered in the hundreds.

Chronology

Punishment and the End of Armorican Sea Power

The defeat ended Armorican resistance for that campaigning season; with no fleet left and no army in the field, the coastal towns had nothing to defend them (BG III.16). Caesar's response was deliberately severe: he had the Veneti's ruling council put to death and sold the rest of the tribe into slavery, a punishment he explicitly ties to their violation of the customary immunity of envoys — the seized Roman officers — rather than to the military threat itself (BG III.16). It was among the harshest reprisals Caesar records against any Gallic community in the entire war, meant to deter revolt elsewhere — though other tribes further north and east tested Rome's frontier commanders again within a few years, including the legates who later held the line on the Rhine under Drusus and Germanicus.

The battle is also one of the few securely dated naval engagements fought in open Atlantic water in antiquity, unlike the Mediterranean ship warfare familiar from Athens's naval buildup before Salamis or the triremes launched from Athenian shipyards. Those fleets fought with rams among light, fast galleys; Brutus's crews faced a wholly different naval architecture and solved it with an improvised weapon rather than a better ship.

Conclusion

The naval campaign against the Veneti rarely gets the attention paid to the sieges of the later Gallic War, but it is one of the more revealing episodes of the conflict precisely because it was not won by Roman strength. Rome's ships were weaker, its crews less experienced with the ocean, and its commander a legate rather than Caesar himself. What decided the battle was a mechanical countermeasure to a specific enemy advantage, followed by weather the Romans could not have planned for. The brutal settlement that followed says as much about how Rome wanted to be seen by the rest of Gaul as it does about the Veneti themselves.

Frequently asked questions

Who commanded the Roman fleet against the Veneti? Caesar assigned command to a legate he calls Brutus, generally identified as the young Decimus Junius Brutus Albinus, who would later serve under Caesar in the civil war and, in 44 BC, join the conspiracy against him. Caesar himself watched the battle from the shore with the land army rather than commanding at sea (BG III.11, 14).

Why couldn't Roman ships simply ram or outfight the Veneti navy? The Veneti ships were built of solid oak with reinforced timbers, making them far sturdier than the lighter Roman vessels built hastily that spring, and their high sides put Roman missile troops at a serious disadvantage. Rome's only real advantage was that oared ships could maneuver better than sailing ships, especially in light or contrary wind (BG III.13-14).

What was the actual tactic that won the battle? Roman sailors used long poles fitted with sharpened hooks, adapted from equipment used in siege warfare, to catch and cut the ropes holding each Veneti ship's sail to its mast. Once disabled, a ship could not maneuver, and Roman crews would surround and board it while the crew was unable to escape (BG III.14).

What happened to the Veneti after their defeat? Caesar had the entire Veneti governing council executed and sold the rest of the population into slavery, a punishment he attributed specifically to their seizure of Roman officers rather than to ordinary battlefield defeat. It was one of the harshest reprisals recorded anywhere in the Gallic War (BG III.16).

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