Short answers, pulled from the story.
Boulogne-sur-Mer is France's largest fishing port, specialising in herring. It is also known for its 12th-century UNESCO World Heritage belfry, the marine science centre Nausicaa, and its long history as a strategic Channel port used by the Romans, Napoleon, and Allied forces in both World Wars.
The Romans first called the city Gesoriacum, then renamed it Bononia sometime between its sacking and the year 310 AD. Both names referred to the same port city, which served as the main Roman base connecting the empire to its province of Britain.
Napoleon assembled La Grande Armee in Boulogne as a staging area for a planned invasion of the United Kingdom. The operation was never launched because other pressures across Europe intervened and the Royal Navy's dominance of the Channel made a crossing too dangerous.
On the 22nd of May 1940, two British Guards battalions attempted to defend Boulogne against the German 2nd Panzer Division and were evacuated by Royal Navy destroyers under fire. On the 15th of June 1944, 297 RAF aircraft including Avro Lancasters carrying Tallboy bombs destroyed the harbour. The 3rd Canadian Infantry Division liberated the city in September 1944 during Operation Wellhit.
Jose de San Martin died in Boulogne-sur-Mer in 1850. He had lived in the city for two years, and the house where he died is now a museum called La Casa San Martin.
The first World Esperanto Congress was held in Boulogne-sur-Mer in 1905, where the Declaration of Boulogne was ratified. L. L. Zamenhof, the creator of Esperanto, was among the attendees. A centenary celebration in 2005 drew more than 500 participants.