Here's a naval & fort commented walkthrough of Assassin's Creed 4: Black Flag from Gamescom 2013.

Game Director Ashraf Ismail takes us deeper into the world of Assassin's Creed IV Black Flag with this new commented gameplay video. Immerse yourself in the Caribbean World with Edward Kenway as he engages and weakens a Fort with the Jackdaw, and seamlessly launch into a ground assault, aiming for the Commander of the Fort.

Assassins's Creed IV: Black Flag is slated for an October 29, 2013 release in North America, October 31 in Australia, November 1 in Europe and November 28 in Japan on the Xbox 360, PlayStation 3, Xbox One, PlayStation 4, Wii U and PC.