@WAB
Out of couriosity, did they get insurance for loss of their property?
But in the line of this discussion, most probably it was not due to ship breaking in half. (althoug possible)
its a matter of stowage.
During rolling, strong inertial forces appear, on stacked boxes, on extreme sides, (biggest radius of roll) which may cause a seaside line of containers to collapse, and start domino effect on the rest of stowage stacks.
Or, a container in lowest part of column, simply collapse, by inertial pressure from top side boxes (tons of cargo on top, pushed inertially downwards during upward roll) crashed by them. Lashing doesnt hold, and entire stack is washed overboard..
If it happens in the hold, lowest container is crashed, others not, but jammed in cargo bay.
Comapny Mearsk was the first to implement "pyramid" stowage, where seaside stack of containers was not more then 4 or 5 boxes in height.
Inner stack, one more, etc.
This kept seaside stack safe, and it kept other more to the center secured.
Later, other companies followed. Sometimes.
But, the consequence is losss of cargo space in seaside stacks. (loss of freight)
Reward, a safe carriage of cargo.
First photo below: pyramid stowage
2nd photo below, box stowage, consequence.
Genrally, loss of cargo can be prevented by smart stowage, or by smart navigation (avoiding storm, reducing speed, skilled manouvering in high swell, etc), or combination of both.
As a user of trasnsport service, sending your container overseas, basically you have no influance. Hope for the best.
