The war in North Africa was won and lost on the Mediterranean Sea, where an interdiction campaign that slowly worked its way up and lasted two years wrought havoc on Axis supplies. While the impact of the campaign has often been overstated, since by volume most supplies came through, this is only one aspect, and we have to be careful not to negate it on this basis.
What the campaign did beyond the actual sinking of supplies was to impose an intolerable burden on the weakest partner in the Axis, Italy, which had to commit most of its naval effort, fuel oil reserves it did not possess, and industrial capacity that it lacked to a continuous battle against a superior enemy. The Italian forces acquitted themselves well in this battle, contrary to popular belief, but this was not enough.
The book is addressing this never-ceasing battle, which was conducted on, above and below the sea, and while I have yet to read it in full, a quick glance already shows that it sets a new standard in the consideration of the campaign in the Mediterranean.
In due course a full review will be provided here.
Further Reading and Ordering
 A good example of the lopsided nature of the conflict is that during Operation CRUSADER, more men died at sea than at land (see this older entry).