The Dardanelles Straight connects the Sea of Marmara to the Eagean Sea and the Bosphorous Straight connects it to the Black Sea

Turkey controlled the Dardanelles

The Dardanelles were known as the Hellespont.

Dardanelles

See the link below. The Dardanelles was not part of World War 2 but rather World War 1.

Editor's note. It was the Brits (namely Winston Churchill, in World War 1, of the admiralty) who wanted to secure the Dardanelles strait to control shipping access. At the time Britain controlled Turkey. There was warring going on there during World War 1. See the link below for the story of the Battle of Dardanelles.