You decide to make a pre-emptive strike on the fort in the early predawn haze.
The wind blows offshore initially, making your landing possible. You get half of your troops landed before the wind changes to a strong onshore breeze and the troops in the fort realize they are under attack. Your hasty ill-advised attack meets with disaster and half of your troops are either killed, captured or drown trying to swim back to the ships. The wind direction prevents your ships from being able to get in close to the fort and from picking up survivors or bombarding the fort.
