The design of the Chesapeake Bay Bridge-Tunnel, specifically the tunnel part, makes a lot of sense now. Imagine a US navy port (Norfolk) being inaccessible if this happened there.
The Navy has long required that the sea lanes from the Norfolk Naval Shipyard and Newport News Shipbuilding to the ocean have a deep-draft passage with no bridge, for just that reason.
Which is why there's a tunnel -- when Virginia looked at replacing the ferry that ran between the Eastern Shore and Norfolk/Virginia Beach, the US Navy objected to a bridge over fears it could collapse. (An accident, sabotage, etc.) That's also why I64 has a bridge-tunnel design, as well.
This was also a major concern around the construction of the Golden Gate bridge; that during a time of war an enemy could have destroyed it to trap a large portion of the Navy's Pacific Fleet in the bay.