Allied D-Day Invasion

The transcript describes the formidable construction of a Nazi fortress, highlighting the military and engineering prowess involved. It then shifts focus to the diverse group of Allied forces from various cities worldwide, who are preparing to achieve what historical figures like Hitler and Napoleon could not: crossing the English Channel to attack the fortified coast on the other side.

From which locations did the boys come to participate in the military action?

What geographical feature did the boys cross to attack the fortified coast?