Parts of a first century Roman warship have been found in Cologne Germany. The first results from the wood samples give a date of 15 A.D. And that makes it the oldest Roman warship found in Northern Europe. The ship seems to be a transport galley propelled by oars and a sail. It could carry a centuria of ca. 80 soldiers with a normal crew of 20 sailors.
At that time - 14-16 A.D. - Cologne (called Oppidum Ubiorum then) was the centre of a massive Roman campaign led by Germanicus against a coalition of tribes led by Arminius, which had successfully overthrown Roman rule in a rebellion in 9 A.D.* It is possible that this ship played a part in the campaing. Tacitus speaks of a new fleet of 1000 built by Germanicus for this campaign.**
Later Cologne was the headquarter of the Roman fleet on the Rhine and the capital the province Germania Inferior.
* Germanicus was the stepson of emperor Tiberius.
** Tacitus Anales, 2.6.2