The Invasion Fleet

 

The tried and true field officers Caecina, Silius, and Anteius were entrusted with the task of building the fleet. This was a gigantic undertaking, as becomes clear if we consider that nearly a thousand ships had to be completed during the four winter months – everything from felling the trees to launching the ships! Even today, with all the technical means at our disposal, it would be a daunting task.

 

The technical data concerning the project are still quite interesting. We know that in ancient times, the construction of an ocean-going medium-sized vessel generally required around four months. Caesar reports that, following procurement of the wood, his fleet of 628 ships (600 built during the winter) set out on his Second Britannic Expedition in the year 53-54 BC.

 

If the construction time that he gives is correct, this means that a team of ten men was able to complete each ship in this relatively short period -- for 600 ships, a shipbuilding force of 6,000 men.

 

Thus, no fewer than 10,000 construction workers must have been employed in the construction of Germanicus’ fleet during the winter and early spring of the years 15/16. A huge number! Even if the specialists from the various legions (such as engineers and carpenters) as well as sailors of the Rhine fleet and indigenous skilled workers were employed, the logistical and nautical task must still have been extremely difficult for the ship building engineers. Such a task could have been completed only if they had adopted three stream-lined ship models, greatly simplified for their specialized use. (The Allies adopted a similar solution during the Second World War when they developed the greatly simplified “Liberty Ships” in response to massive losses to German submarines.)

 

The military and nautical requirements were varied. They were constructed not as warships, but as big-bellied Actuaria or riverboats to transport troops, horses, and supplies.

 

Thus, Germanicus’ fleet consisted almost entirely of cargo ships.

 

All three types were decided to have as great a capacity as possible, with shallow draft and flat keel so that they could travel as far as possible up the German waterways and beach on the river banks.

 

Since these were riverboats, the railings could be kept lower, while the sterns were wider than normal. This tended to destabilize the vessels during ocean travel,. They were powered by both oars and sails, and they were also outfitted with Scorpione (missile catapults) for defense against attacks from the bank. In addition, rudders were added to the bow in order to increase maneuverability in time of danger.

 

If Germanicus’ specialists advised that he would need 1000 ships for his campaign, they must have included the space required for horses and materiel as well as provisions, which of course depended on the anticipated length of the campaign. All in all, the entire massive project involved a very large number of nautical, technical, military, and logistical considerations, and these in turn required a great many precise calculations.

 

The tonnage of these riverboats varied greatly -- between 30 and 1300 tons, depending on water depth. Based on the figures of Caesar’s first invasion of Britannia, we find that he loaded two legions of 6,000 men each onto 80 transport ships. This means that each ship carried around 150 men and 33 horses. Applying this ratio to Germanicus’ fleet, we find that for 90,000 men, 20,000 horses and 960 supply wagons he would have needed the capacity of at least 600 ships.

 

For this number of men, horses and wagons, in addition to the accompanying baggage train of 8,500 wagons with guards and around 17,000 draft horses, military statisticians have arrived at a total load requirement of around 25,000 tons for a spring or summer campaign lasting three to four months.

 

Of course this rather high tonnage applies only to completely combat-ready units, including accompanying auxiliary troop contingents.

 

This figure is probably quite accurate, since it includes replacement weapons, munitions, and all kinds of spare parts as well as medical supplies, heavy weapons (catapults) and pioneer (construction) implements. In order to transport such cargo, an additional 400 ships were necessary with each ship carrying around 64 tons (4 railroad cars of 16 tons each). All these make a total of around 1,000 ships.

 

The number of transport ships, that initially seemed very high, appears entirely credible In view of the above. Probably the remaining parts of the Rhine fleet that survived the first campaign were also used, with slight refitting.

 

We should consider that the baggage train wagons could be disassembled for compact storage. After landing they would have to be reassembled immediately in order to accompany the troops as they marched inland.

 

The ship components probably consisted of Spanish metal fittings, sails and lines. Esparto grass, which was used in the manufacture of ships’ tackle because it withstood exposure to salt water, was grown in Spain.

 

As we have noted, the standard type of fleet cargo vessel was the so-called Actuaria. It was propelled by 15 rowers on each side, which leads us to estimate a length of 20 to 23 meters and a midship width of around 6 meters. These ships had a short foredeck and afterdeck on which, in addition to individual Kanzel (cockpit) amidship, there were also battle stations for archers and missile launchers. Except for the necessity of keeping dry the provisions for men and animals, these boats dispensed with totally covered solid decks, which spared the boats considerable weight. Perhaps they simply covered their provisions with the legionnaires’ tents, which were then stored at different locations after debarcation.

 

We do not know whether the teams of oarsmen were covered by the overhead walkways that ran along the railings from stem to stern, or not. In the horse transporters, which were certainly open, the oarsmen may well have been protected by dividing walls that were designed to distribute and tether the animals throughout the cargo area of the ship.

 

In order to transport 33 horses per ship, three to five animals were tethered alongside each other lengthways on beams running from larboard to starboard, so that they stood across from each other. They were brought on board by means of a ramp directly above the railing.

 

If we assume, in view of the small size of horses in those days, an average length of 205 cm per animal, and if we allow corresponding space for movement and fodder, we arrive at a ship’s length of 23 meters, which has in fact been documented.

 

In addition, the actuaria were outfitted with steering rudders at both bow and stern, which, with their relatively shallow draft (70 cm empty, 90 cm loaded), enabled them to change direction much more quickly than the clumsier warships, which had a draft of up to 1.5 meters.

 

Their sails were four cornered Rah sails, which were around 14 meters long and 10 meters high. The mast was as long as the sail was wide.

 

In addition to the actuaria, which were designed especially to support invasion by foot soldiers, several liburnia would certainly have accompanied the fleet. These were medium sized warships having shallow draft (75 – 90 cm) that accompanied the transport convoy as escorts. These were around 21 – 23 meters long and 3.5 meters wide that were outfitted with a rammer. They were propelled by two rows of oarsmen one above another, with 22 oars on each side. Thus they were fast moving ships, which could also be propelled by sails. The crew consisted of captain, a sailing master, four sailors and 10 marine infantry. At the debarcation site, these ships probably served as a kind of floating fortress to protect the tents on the river bank of the camp, where provisions were stored.

 

The entire convoy of ships was headed by Germanicus’ flagship. This was a triere, which was a particularly fast ship propelled by three banks of oars. We do not know the precise type of triere he used. The largest version had a crew of 150 placed one above another for a total of three rows of 25 oarsmen on each side. These oarsmen were not slaves! Germanicus apparently preferred a somewhat more maneuverable triere having 72 oarsmen, with 36 on each side. The length of this type ship was normally around 35 meters and the width 5 to 6 meters, with a draft of around 1 meter. Like all larger warships it was outfitted with rammer and combat platforms. In addition to the oarsmen, the crew consisted of nautical and military personnel, namely 12 sailors and 80 – 90 marines.

 

The Romans, attempting to extend their invincibility on land to invincibility at sea, carried the tactics of land warfare over to the planks of their ships. There they were trained to fight just as they fought on land with sword and shield, deck to deck and man to man.

 

A captain, steersman and sailmaster were responsible for nautical parts of the undertaking, while a centurio was in charge of the marine soldiers, just as in the army. If the nautical situation was the primary concern, the captain was also in charge of the marine infantry.

 

The cabins of the commandant and ship’s officers were in the stern, and there was a tent-like arbor above the afterdeck. There, or else on the foredeck, was also a tower-like metal-clad structure decorated with painted stone blocks to resemble a masonry battle tower. From atop this “stone tower” catapults, archers or spear throwers could defend the ship from a higher elevation.

 

All the ships must have been terribly crowded. The legionnaires and crew members had to sleep very close together on deck, next to their horses or at their battle stations.

 

The ships of course had to debark in as still water as possible. It is more likely that debarkation would have taken place on the middle Weser or in the vicinity of Porta Westfalia than on the Ems. There the huge army with all its supplies and baggage train would have had to cover the distance of 230 kilometers from the Ems to the Weser in a march lasting at least 10 days, in a column at least 60 kilometers long. Germanicus would most certainly have wanted to avoid such a march for security reasons, as well as avoid tiring his troops.

 

Furthermore this added distance would have caused him to lose the advantage of surprise and would also have been made logistics more difficult. For these 10 to 12 days alone, additional provisions for men and animals would have to be transported a marching distance of 30 kilometers.

 

In addition, Arminius would not have missed the numerous opportunities to ambush a slow-moving, serpentine army that was 90 kilometers long. He would have continually attacked from the heights of the Wiehen mountain range or cut off the endless supply columns. Germanicus could never have reached Cheruskan territory “with fresh forces and without bloody losses” as he had proposed to Tiberius.

 

Furthermore the overland march from Castra Xanten to the middle Weser by way of Haltern-Oberaden-Bielefeld-Porta was 50 kilometers shorter than the stretch from the mouth of the Ems River. It is clear that the entire gigantic expenditure of materiél would have been worthwhile only by using the Weser as approach route.

 

We can assume that part of the supply fleet was anchored in the vicinity of Verden, presumably in the Wümme Depression. At that time, there was a large lake on the Weser, where the ships could be unloaded in quiet waters. Another part of the fleet probably anchored further south in the vicinity of Porta, at the departure point for “Operation Elbe.” Here the main east-west conjunction of the “Hellwege” offered the shortest and best marching route.

 

Germanicus hoped to shorten the dangerous and fatiguing overland march by means of ship transport, which would allow him to deliver his legionnaires into the heart of Germania rested,well equipped and ready for action.

 

This ancient trade route led over a river crossing eastwards past Minden and along the Harz mountain range to the Elbe river. This was the most favorable spot to establish a bridgehead and construct a bridge, where Germanicus could cross the Weser and begin his grand offensive. During his Saxon wars, Charlemagne also crossed the Weser many times at the ford near Minden. The area north of where the Weser cuts through the mountains was also a favorable place to keep the ships as closely together as possible. There, the river divided into three wide and sheltered streams interspersed with sand banks that are now dry land. The river flowed slowly and offered an ideal anchorage in a relatively narrow and restricted space.

 

If the thousand ships had tied up stem to stern along the bank of the river where it flowed rapidly, they would have required a debarkation stretch of no less 30 kilometers. If they had anchored in a “packet” tied hull to hull, they would still have extended 15 kilometers, which would not have been conducive for establishment of a convenient central supply site. In addition, they would have been closer to the mouth of the river, where the current was much too strong. After debarkation, the ships would presumably have been guarded only by their nautical crews, since the bulk of the marine infantry would have been assigned to battle groups of the various legions.

 

The actual costs of Germanicus’ mammoth armada construction program can hardly be estimated, but they must have been enormous. Without doubt, the planning and execution were remarkable. Organizationally and technically, construction of the fleet was a masterful accomplishment. However, it was part of the ill-starred and tragic destiny of Germanicus that his gigantic “River March” campaign, which is considered the greatest amphibian assault of antiquity, never produced any real successes.