Interesting doc on Channel 5 (UK) referring to the nature of the WW2 D-Day training disaster at Slapton Sands and how the suggested death toll (which included friendly fire and deaths through poor planning over e boat attacks) is much higher than suggested (although acknowledged by some sites)! Seek it out if you're interested
There is no question that Tiger was a military disaster. Part of this was due to infighting between the Army and Navy. For several years, the Navy had been working with the Marines on Amphibious Assaults in the Pacific. And they had learned a lot of lessons from this (like life vest training, standardized radio frequencies and procedures, and abandon ship drills). The Army however refused to learn from these lessons, and insisted that things be done their way. And the result was a disaster. Soldiers jumped into the water with their full combat packs, or without their vests put on properly. The US Navy, Army, and British Navy did not operate on the same radio frequencies and had different procedures, so messages between them were unable to be sent (or sent wrong, REPEAT in the Army means to send the same fire mission, in the Royal Navy it means to repeat the last message, so a garbled message sent to one that then asked for the same message again {stop firing} resulted in a continuation of fire). However, at least they took the lessons strongly, and fixed the problems so that when D-day actually happened, there was less of that kind of problem.
