The new unit's first task was to form part of the force at Boulogne for the Napoleon's planned invasion of the United Kingdom. They built boats for the force and served in their primary role as an elite unit to bolster naval crews, which often had little training or experience. When the invasion was called off, part of the unit fought in the 1805 Austrian campaign, fighting at Ulm and Austerlitz. Then, in 1806, 102 men from the unit took part in the Prussian campaign, fighting at Jena and especially in the siege of Danzig, where they formed part of Chasseloup-Laubat's force of engineers. Finally, they followed the Grande Armée into Poland, where they were re-joined by the crews who had remained in France. Together they then fought at Eylau and Friedland.