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Nathan Ross · 03-31-2003, 06:35 PM

Hmm, second post in one day - I must try not to seem too eager... Anyway - I'm a bit puzzled by a passage in Caesar's 'Gallic War', and I wondered if anyone could help me out. It concerns the campaign of the 'land army' against the fortified coastal towns of the Veneti in 56bc (before D.Brutus assembled his navy and defeated them at sea, that is). The Veneti, Caesar says, withdrew to their fortifications and proved very difficult to dislodge, as: 
 
"The sites of their towns were generally such that, being placed on extreme points [of land] and on promontories, they neither had an approach by land when the tide had rushed in from the main ocean, which always happens twice in the space of twelve hours; nor by ships, because, upon the tide ebbing again, the ships were likely to be dashed upon the shoals. Thus, by either circumstance, was the storming of their towns rendered difficult..." 
 
He therefore captures the fortifications as follows: 
 
"...the sea having been excluded by a mound and large dams, and the latter being made almost equal in height to the walls of the town..." 
 
What, though, does the above passage actually mean? 
 
The Veneti, I believe, lived around the Bay of Morbihan in southern Brittany, where there are to this day many small islands close to the shore and connected only by causeways at low tide. These would seem to answer to Caesar's description as a site for the Veneti forts. But what about these mounds and dams? All I can imagine is that: 
 
A. An enormous siege ramp was built from the shore (at low tide) to the walls of the town - this would have to be of great length and great height, to top the walls at its furthest extent, and be able to withstand the twice daily inrush of tidal sea. Quite an engineering feat? Or... 
 
B. Two dams were built parallel with the causeway, blocking off the sea at either side and creating an area of dry land over which troops or siege machines could pass. Again, rather a spectacular achievement, especially considering that the furthest ends of these dams would have been built directly under the walls of the town and the missiles of the defenders. 
 
Can anyone clear this one up, or perhaps direct me to an in-depth examination of the BG which might provide an answer? 
 
Thanks!

Jeroen Pelgrom · 04-02-2003, 06:22 AM

Salve, 
 
a really good book about the militairy campaigns of Caesar is the book : 
 
Caesar (: A History of the Art of War Among the Romans Down to the End of the Roman Empire, With a Detailed Account of the Campaigns of Caius Julius Caesar) 
 
by : Theodore Ayrault Dodge 
 
my favorite about Caesar. You can by it through amazon : 
[url=http://www.amazon.com/exec/obidos/tg/detail/-/0306807874/qid=1049268137/sr=1-17/ref=sr_1_17/102-5409824-5328944?v=glance&s=books" target="top]amazon.com[/url] 
 
i believe that this event is mentioned in the book. I'm at work now, so can't check. 
 
gr, jeroen

04-02-2003, 12:05 PM

Hi, 
 
It's curious that Veniti towns were not approachable by sea as they were a seagoing tribe ? Maybe this was meant to mean in Roman galleys ? 
 
Ceasar did some amazing things with siege works so what you describe Nathan seems to fit the bill. 
 
Conal

Jeroen Pelgrom · 04-02-2003, 01:35 PM

Salve, 
 
this episod is indeed in the book of Dodge (pag. 131 - 139) : 
Dodge says : 
 
"The Roman method of taking the Venetan towns was to build out from the main land two parallel dikes, sometimes as high as the town walls, which when completed excluded tides and gave an excellent approach for engines and men - a place of arms, in fact. It was a vast labour and the operation was rendered nugatory in most cases by the escape of the barbarians as above explained" (the Veneti escaped with their ships). 
 
Dodge had visited all the battlefields (in 1890) so this is propaply true. 
This is B with you... 
 
gr, jeroen

Nathan Ross · 04-02-2003, 06:40 PM

Thanks Jeroen - I'm definately going to have to get a copy of the Dodge book. I wonder if his visit to the site provided him with evidence of these dikes, or whether, as a military man, he just concluded that this was the only feasible way of doing it? I've seen aeriel pictures of some of these Breton islands, and there's quite a gap of open water between them and the shore at high tide. 
 
As for the Veneti in their boats - the towns obviously were accessible by water, as that's how the besieged made their escape when Caesar broke through the fortifications. I'm guessing they were using very shallow draught boats to do this, such as might be used in the tidal waters of an enclosed bay - Caesar's comment about the water being too shallow and rocky for ships would therefore refer to the kind of ships the Romans had available at the time.

Jeroen Pelgrom · 04-03-2003, 06:41 AM

Salve, 
 
i recommend all the books of Dodge (Caesar, Hannibal, Alexander and Gustavus Adolphus), very usefull (though ignore the "roman mercenaries" theory, bit oldfashioned). Dodge only describes the militairy stuff of Caesar, not his political! Dodge was a soldier/ officer in the US army, i think that this conclusion is a militairy one. By my knowledge they haven't found any dykes there, so we are only guessing here. There is a small picture in the book of the attack on a Venetan town. The Venetan town is a small island, close to the Atlantic coast. If i consider the other Roman sieges, the two-dykes theory is more propable. On top of the dykes they would place the artillery to shoot the defenders of the walls, giving the Roman soldiers enough protection to fill in the gap of water (dodge gives a detailed account on Roman sieges). 
 
gr, jeroen

01-27-2004, 02:43 AM

The agger, a siege method, was a pile of dirt and stones against a wall to permit soldiers to breach it. Caesar built one 330 feet wide and 80 feet high in 25 days while besieging Avaricum. Alexander spent 8 months building one at Tyre. Moveable towers defended the men building the agger. 
The sturdy oak ships of the Veneti had flat bottoms and leather sails, but no oars. They could be safely "beached" on rocky shores while Roman ships could not. Caesar ordered similar ships built in the Loire River and Brutus arrived with them, and some Roman ships as well, to battle the Veneti at sea. The Romans cut the rigging of the Venetian ships, and the wind died, leaving the heavy ships becalmed and helpless. The Roman ships swarmed them individually and overpowered the sailors. Some Venetians dove into the water to drown rather than be taken.

03-07-2004, 01:45 AM

The Roman agger was a mound of earth, stones, and timber built up against the wall of a fortress under siege. As the mound grew, the attackers had a better chance to fire arrows and projectiles over the walls. The men building the agger were protected from enemy fire by vineae, portable huts made of wooden frames with a covering of wattle, bundles of sticks and brush. Vineae were also positioned at the base of the walls for miners to dig under the fortifications. Portable towers and turrets were moved toward the besieged city or fort to give the attackers a higher firing position. 
 
When the agger was high enough, the attackers could breach the walls. Caesar built two against the walls of Marseilles during that siege a few years before the campaign against the Veneti. 
 
When the siege target was protected by water, the agger was an earthen pier built through the water until it reached the walls. Alexander took eight months to build one to capture the island city Tyre, and the structure remains as a land bridge. 
 
The agger was not a pair of walls built out into the water. The tide would have flooded the space between the walls, and even if the tidal flat could have been kept dry somehow, it would not have been a suitable position from which to attack the high walls. The space between the pilings would have been filled with earth.

Nathan Ross · 03-07-2004, 03:24 PM

Smild - my original post was prompted by just these considerations. What Caesar wrote, however, was that 'a mound and large dams' were built, 'the latter' (ie the dams) to the height of the walls. This indicates that there was one mound (by which he could mean the agger, although I don't have the latin text to check) and at least two dams. He also writes that 'the sea was excluded', suggesting that some area of dry land was created by the operation - one single agger would indeed exclude the sea from its immediate area, but then why were the dams needed as well? It would seem that the dams were built as parallel walls, and the mound filled the space between. As Caesar writes that the sea only cut the forts off from the land at high tide, we can guess that there was a dry causeway at low tide - as at Mont St Michel in Normandy or St Michael's Mount in Cornwall today. This means that the sea would not have been very deep over this area at high tide - rather than building one huge agger across the gap, Caesar seems to have decided that the two parallel walls - the 'large dams' - with the 'mound' between would have been less time consuming - I would guess that the 'mound' in this case only needed to be high enough to provide a secure platform for siege engines to be brought within range of the walls, with the actual assault being mounted across the 'dams' on either side.

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