The Boulogne camp refers to two military camps established around Boulogne-sur-Mer in France.
The first camp was prepared by Julius Caesar in 54 BC to prepare the fleet for his second expedition to Britain. One hypothesis is that Caesar set up his camp at the current location of the old City of Boulogne-sur-Mer. Some historians believe that the Old City was built on the camp; at a vicinity to Itius port which he cites in Chapter IV of its Gallic Wars:
The second camp was established by Napoleon Bonaparte in 1803 and continued until 1805. It was here he assembled the Armée des côtes de l'Océan (Army of the Ocean Coasts) or the Armée d'Angleterre (Army of England) to invade Great Britain.
On May 16, 1803, Britain (without a previous declaration of war) seized a hundred French and Batavian ships. France then declared war and Napoleon chose Boulogne-sur-Mer as a base for attacks.
The Boulogne camp housed about 60,000 soldiers in 1805, and was divided into two large camps:
At the top of the cliff were the command barracks, including that of Napoleon, but the headquarters was located at Castle of Pont-de-Briques.[1]