[Gay State Conservative]

This old Army guy knows basically nothing about the Navy...but it's easy to see that the sinking of any naval vessel would catch the attention of top brass!

[ExSafecracker]

I assume this vehicle was an LCM (landing craft marine). They look pretty much like a combat tank, but without the big gun turret.
I think they have 2 large Rolls Royce engines, 1 for propulsion and 1 mainly as a water pump. My amphib ship could carry 6 or 8 of these things. We launched several in Okinawa as demo/training back in 1968 or 69, and one sank in fairly shallow water just off the beach. No lives were lost and we did salvage the vehicle. Word was that the pump engine stalled and it sank like a stone.