The seaport city that was the scene of thousands of allied troops being rescued by boats was called
paris
hamburg
dresden
dunkirk

Dunkirk

Step-by-step explanation:

Dunkirk is a coastal city in France, where the allied troop were gathered and cornered by the German Army, the civil boats left Britain and were sent to the dunkirk shores to transport the allied army all the way back to England where they were safe again, if this operation hadn´t take place most of that army would have died because they were already surrounded by the enemy and the allied forces would have been largely decimated.